10

Exercise

Movement matters

A septuagenarian colleague of mine, visiting from San Diego, broke his hip after slipping on black ice in Montreal. He was bedridden for months. In fact, he never really recovered, and although he lived another seven years, those years were painful and frustrating for him and all who knew him. Why? You might think that something physical, like a hip injury, would have no bearing on his mental state. But we humans were not made to be sedentary. We evolved in a world that required us to explore the environment, to move. Without that stimulation the brain ceases to function at its full potential … and can easily go into a tailspin.

In his new book, Physical Intelligence: The Science of How the Body and the Mind Guide Each Other Through Life, Scott Grafton, a neuroscientist and practicing neurologist at UC Santa Barbara, proposes that the enormous complexity of the human brain is primarily there to organize movement and action. When we cease to move, to explore our environment, when we no longer use our brains to organize physical action, could it be that it slows down, atrophies, and becomes disorganized? If that were so, how can we account for people like Stephen Hawking and Jean-Dominique Bauby (the guy who dictated an entire book—The Diving Bell and the Butterfly—with blinks of the eye)? Are these individuals exceptions?

When I posed this question to Dr. Grafton, he explained:

I can’t speak for two geniuses who had entire staff keeping them alive for an extended period.1 Put enough effort into it and you can grow a rose bush in the middle of the Mojave Desert. Nor am I saying that not being physical makes you stupid or atrophy.

Rather, we can ask, how to best maintain whole organismal health and well being for anyone? Step one is to eliminate the brain/body dualism. Just because some aspects of mental life and mind are intuitively separable from brain, doesn’t mean the brain (or mind for that matter) is ever really free of the body.

Step two. What is the single factor with the largest effect that benefits mental health, body structure (including brain structure), functioning across multiple domains, and longevity? It is physical activity (or its imprisoned corollary, “exercise”). We’ve now had hundreds of trials with thousands of subjects.

Step three. Why is all this physicality good for us? Well, there is a long list of probable reasons. My book touches on just those that make sense from a perspective of movement science: skill, adaptation and perceptual fidelity in the natural world. But there are lots of others—problem solving, social enrichment, mind-body coordination, and fresh air.

Grafton’s findings are based on the idea that at the most fundamental level, the brain is a giant problem-solving device.2 Furthermore, most of its problem-solving capabilities evolved to allow us to adapt to a wide range of environments. Ten thousand years ago, humans plus their pets and livestock accounted for about 0.1 percent of the terrestrial vertebrate biomass inhabiting the earth; we now account for 98 percent. Our success is owing in large part to our problem-solving, adaptive, and exploratory brains.

Our brains were built to move our bodies toward food and mates, and away from predators. Exercise is important for two reasons. The obvious one is that it oxygenates the blood. The brain runs on oxygenated glucose, carried by hemoglobin in the blood, and a fresh supply of oxygen is good. The nonobvious reason is that our brains, because they were built to navigate in unfamiliar surroundings, don’t do well when they’re not challenged by having to problem solve. Every step you take on a treadmill or elliptical is helping you with the first of these two imperatives—getting your blood oxygenated—but they don’t help your brain to keep its navigational skills and memory systems honed. Every minute you walk on an unpaved trail, whether in a park or in the wilderness, requires you to make hundreds of microadjustments to foot pressure, angle, and pace. These adjustments stimulate the neural circuitry of your brain in the precise way that it evolved to be used. The area that is most stimulated is your hippocampus, that seahorse-shaped structure that is critical to memory formation and retrieval. This is why so many studies show that memory is enhanced by physical activity.3

This way of looking at things is known as embodied cognition, the idea that physical properties of the human body, particularly the perceptual and motor systems, play an important role in cognition (thinking, problem solving, action planning, and memory).4 In this way of thinking, the sensation of movement is inextricably bound with knowledge.5 Embodied cognition is consistent with this book’s developmental cognitive neuroscience approach. It sees humans as embodied, ecologically and genetically embedded social agents who shape and are shaped by their environment.6 The body influences the mind just as the mind influences the body.7 Embodied cognition puts intelligence and control out in the body. The best example of this is the spring ligament in the arch of the human foot. This dumb little spring eliminates the need for a massive feedback control circuit in the brain to give the toes a nice little push-off during walking.

If you have a cartoonish version of the different characters you went to high school with—the nerds versus the jocks—you may see them as holding down opposite lifestyle choices: The nerds, ever bookish, shun physical activity in favor of the more refined rewards of deep thoughts. The jocks, ever boisterous and active, shun the dull, nerdiferous, and slow-moving pace of reading, writing, and ’rithmetic. And although such characters surely exist, the most successful intellectuals are those who embrace the physical, and the most successful athletes are those who embrace the intellectual. Among my university colleagues, those who keep physically active are by far the most productive, from my collaborator James Ramsay—the one who rode his bicycle across the Canadian Rockies in his late sixties—to my wife, Heather, who is a distance runner and rock climber. I’ve recently had the opportunity to meet with top college and NFL players, including five-time Super Bowl winners (to discuss the effects of repetitive head injuries on cognition in later life), and they are as smart, inquisitive, and intellectual as anyone I’ve ever met in a university.

After a particularly stimulating conversation with Yauger Williams, a former Cal Bears right guard, he leaned back and said, “You know, this is great. And this is the closest I’ve ever been to an actual neuroscientist.” I said, “It has been great. And this is the closest I’ve ever been to a football player without having my head flushed down a toilet!” (He laughed, a bit too knowingly.)

A systematic meta-analysis showed that for adults with mild cognitive impairment, exercise had a significant beneficial effect on memory.8 Adults with mild cognitive impairment have a considerably increased risk of progressing to dementia, and this specific risk is increased by atrophy of the hippocampus.9 Physical activity may be just as effective as pharmaceutical agents in improving and maintaining memory, as well as global cognition, and delaying the onset of dementia and other neurological diseases such as Alzheimer’s and Parkinson’s.

Aging is an irreversible and inescapable process.10 But the effects of aging are, in some cases, reversible and, if not completely escapable, at least subject to delay. There are many factors under our control—diet, gut microbiota, social networks, sleep, regular visits to the doctor. But the single most important correlate of vibrant mental and physical health is physical activity. This doesn’t mean the other correlates (diet and sleep) aren’t important—they are—and it doesn’t mean that if you engage in more physical activity you don’t need to follow other healthy practices. What it does mean is that you might want to take this seriously—particularly if, like many people, your attitude about getting active is “Yeah, yeah—I’ll start tomorrow.”

As Scott Grafton points out, physical activity is not the same as exercise. It’s moving around, interacting with the environment. As Cicero knew, it is this kind of interaction that “supports the spirits, and keeps the mind in vigor.” Running has benefits, but so does walking, even with a cane or a walker. The physical activity doesn’t need to resemble the kind of workout that twenty- or thirty-five-year-olds might do. It’s important to respect your body’s limits and to consider age-related factors. Older adults should check with their doctors or work with a professional trainer to determine what kind of movement is right and appropriate for them. If you can run marathons like ninety-two-year-old Harriette Thompson did, that’s great—but you may find that you get substantial benefits simply from lifting five-pound free weights in your bedroom and walking around the block at a slightly faster than comfortable pace.

Looking at memory, movement, and embodied cognition as being interrelated helps to explain one of the biggest mysteries of human memory: infantile and childhood amnesia. Generally speaking, we don’t remember anything from our first two years of life, and only a little before age six. (People who claim to have vivid memories of early childhood are often mistaken and are reporting stories that were told to them by parents or siblings, or mistaking photographs of events for primary memories of those events.) If memory evolved to help us with spatial navigation, the reason that very young children have no memories is because they are not moving around and interacting with the environment very much. Although children, even before they can walk, are eager to explore the space around them, it appears that the onset of walking triggers neurochemical activity in the hippocampus, prompting the hippocampal place cells and grid cells to begin their internal mapping of the environment.11 Place cells encode particular locations, and grid cells encode the relations among those locations. Even though most children have been moving around and exploring the environment by age six, it may take time for the hippocampal place system to mature to the point that it can accurately encode spatial memory in an adult-like fashion. Hence a lack of infantile and childhood memories.

An implication here is that as older adults begin to move and explore less than, say, young or middle-aged adults, those hippocampal-based memory systems might atrophy—use it or lose it, as the professional athletes say. The central role that the hippocampus plays in general, not just in spatial memory, can additionally account for other cognitive impairments often seen in less active older adults—including decrements in reasoning, hand-eye coordination, and problem solving, as well as general cognitive slowing.12

The embodied cognition view further states that our cognitive and perceptual abilities are not a static endowment but rather emerge from fruitful and active exchanges with the environment.13 As children, we gain a sense of agency and control over the environment through our interactions with it—playing in the sandbox, playing on a jungle gym. We can lose that sense of agency and control if we reduce our interactions with the environment, which can lead to a loss of motivation and confidence in our ability to deal with our environment, setting off a downward spiral. This is particularly a problem for older adults who are already experiencing three kinds of bodily changes that may spur them to interact with the environment less.14 First is loss of dexterity, which comes from a general slowing down of nerve transmission speed, loss of nerve conductance, and reduction in eye-hand coordination. Second is a loss of motivation, which may be born of isolation and feelings of loneliness. Third is a loss of joy and pleasure at doing things for oneself, partly owing to reductions in the production and uptake of dopamine, the brain’s reward-chemical signaling channels.

Taken together, these can lead people to curtail activities unnecessarily—that is, not for health or safety reasons. Abandoning a particular activity, such as walking on uneven terrain, or slicing vegetables, leads us to perceive ourselves as “someone who doesn’t perform these kinds of actions anymore” and creates a growing self-image as a nonagent in the world. This can be one of the worst things about aging.

I’m not suggesting that older adults should engage in activities that are unsafe. If you or a loved one has a balance problem, or find you just can’t safely handle a sharp knife anymore, those are very real considerations. But it’s important to take an honest and fair assessment. Fear or trepidation about engaging in activities you’ve enjoyed your whole life just because you’re “old” might not be a legitimate reason to abandon those activities—and may actually accelerate your entry into true “old age.” Six women I know received knee replacements in the past year, and they range in age from fifty-two to eighty-four. James Adams, the “outside the box” Stanford mechanical engineering professor I mentioned in Chapter 4, is eighty-five now, and the last time I stopped by to see him, he had a fleet of antique tractors in his yard and was restoring and rebuilding their engines, a favorite pastime for him. Mick Jagger (age seventy-five) works with a personal trainer.15 “I train five or six days a week …. I alternate between gym work and dancing, then I do sprints. I’m training for stamina.” Jane Fonda (age eighty-one) works out every day with long walks and weights.16 As Dylan Thomas advised, they are not going gently into the night.

Interacting with the world also enhances creativity.17 The interactions don’t have to be especially complex, and they certainly don’t have to be boundary pushing or dangerous. Older adults who were allowed to walk around an outdoor landscape freely, compared to those who were made to walk around a rectangular path, showed significantly higher scores in a battery of creativity tests, including a divergent thinking task—we saw these in Chapter 4, on problem solving. The researchers asked participants to generate as many uses as they could for an everyday object—in this case chopsticks. Sample answers that indicate divergent thinking included using them as drumsticks, as a conductor’s baton, as a child’s magic wand, as a coffee stirrer, or to toast marshmallows. You get the idea. And the researchers found that simply walking around outside enabled a person to come up with more answers.

You may have noticed that thus far in this book I have scrupulously avoided pinning down what I mean by “older adults.” This is because it’s all relative and subject to a large number of factors including disease history, weight, stress, and genetics. There are fifty-year-olds who are unhealthy and ninety-five-year-olds who act and feel more like sixty-year-olds. To me, “older adults” are those who are manifestly slowing down, physically and mentally, who can’t do many of the things they used to do, and who are discovering that the things they might want to do are becoming constricted by physical and mental limitations.

A large part of the story of people who manage to stay young, in spite of their chronological age, relates to synaptic plasticity—the ability of the brain to make and form new connections. As we’ve seen, plasticity is influenced by your genetic makeup, your lifetime of experiences, and the culture in which you live. It is also influenced by your daily routines, especially as you get older. The act of transmitting information across synapses, and the forming of new synaptic connections, requires a dramatic increase in the amount of energy used in the brain. Astrocytes, a type of brain cell, serve as suppliers of that energy. A mounting body of evidence shows that physical activity increases the effectiveness of astrocytes and thereby enhances synaptic plasticity, memory, and overall cognition.18

In addition to synaptic plasticity, cognition is maintained and enhanced by neurogenesis—the growing of new neurons. As we saw in the memory chapter, the adult hippocampus grows seven hundred new neurons per day on average, and there does not seem to be a decline with normal aging.19 Physical activity has been shown to increase hippocampal neurogenesis in rodents.20 It’s not possible to observe any such changes in humans, but we have observed improvement in memory for human adults who engage in aerobic physical activity.21 Most effective is to engage in aerobic exercise just before learning something new. When you get your heart rate up just before a mental task, you prime the brain with increased blood flow, which creates an enriched setting for mental activity.22

Different kinds of physical activity confer different benefits. Physical activity can be categorized as either aerobic or anaerobic. The American College of Sports Medicine (ACSM) defines aerobic activity as “any activity that uses large muscle groups, can be maintained continuously and is rhythmic in nature.” It includes swimming, cycling, running, dancing, and walking. It’s called aerobic because aerobic means “living in the presence of oxygen,” and these activities leverage the body’s ability to use oxygen to extract energy from carbohydrates, amino acids, and fat. The ACSM defines anaerobic activity as “physical activity of very short duration, fueled by the energy sources within the contracting muscles and independent of the use of inhaled oxygen as an energy source.” It includes things like strength (weight) training and short-distance running. (Note that Jane Fonda’s current, age eighty-one workout includes both.)

Aerobic activity is the kind that reduces risks of heart disease and promotes the kinds of cognitive functions we’ve discussed so far.23 Anaerobic activity can help to build muscles, increase your endurance and ability to withstand fatigue, and decrease body fat.24 It can also have a small beneficial effect on cardiovascular risk and lipid profile.

Sarcopenia is the loss of muscle tissue—similar to what osteoporosis is for bone.25 It is a leading contributor to functional decline and loss of independence in older adults. Fortunately, it can be reversed. In one study, twelve sedentary men aged sixty to seventy-two significantly increased their leg strength and muscle mass with a twelve-week strength-training program three times a week.26 In another study, eight weeks of resistance training created significant improvements in frail nursing home residents aged ninety to ninety-six.27 They saw a 174 percent gain in strength, and walking speed improved almost 50 percent. So it’s not just about endurance or blood oxygenation—maintaining muscle strength is essential as well.

Of course, interacting with the environment isn’t always possible—weather conditions in much of the world during winter make going outdoors uncomfortable and, as my colleague in Montreal who slipped on the ice found, sometimes dangerous. So we turn to indoor fitness. Although embodied cognition says that interacting with the environment is best, avoiding sedentarism is crucial. Adults aged sixty to seventy-nine years who engaged in indoor aerobic training showed increased brain volume in the frontal and temporal cortices as well as larger white-matter tracts.28 These findings are significant because these formerly sedentary oldsters exhibited healthier brain measures even when aerobic exercise was first initiated later in life.

Minimal Movement; High-Intensity Interval Training

As we age, we do have a tendency to stop moving. For some people, sedentarism starts around age fifty, for others around age seventy, and some never slide into it. But as we’ve seen, this lack of movement can be the source of many of our problems.

Ulrik Wisløff is the head of the Cardiac Exercise Research Group at the Norwegian University of Science and Technology and a member of the American Heart Association Statistics Committee. He started something of a revolution about fifteen years ago when he published research showing that even a little bit of physical activity can be transformative for brain health and longevity. Wisløff has developed a high-intensity, short-interval program that confers many of the benefits of more conventional, serious workouts and can be done in just three days a week in sessions of about twenty minutes each.29 Even in this overcaffeinated age when all of us have so much to do, surely anyone can find an hour a week to do this. The payoff was significant, reducing the risk of heart attack or angina by up to 50 percent.30

For those who don’t want to do more, but really want to do less, Wisløff and others have shown that even shorter, less structured workouts are still remarkably beneficial. High-intensity interval training (HIIT) is a very short workout—thirty seconds to a minute of running, climbing stairs, or cycling—followed by a minute or two of cool-down activities, such as walking or slow pedaling. Repeat the cycle for only ten minutes and you’ve just done a HIIT. “While anything helps, a bit more is probably better,” University of Michigan researcher Weiyun Chen commented.31

Todd Astorino, a professor of kinesiology at California State University San Marcos, who has published more than twenty papers on HIIT, explains, “We now have more than 10 years of data showing HIIT yields pretty much the exact same health and fitness benefits as long-term aerobic exercise, and in some groups or populations, it works better than traditional aerobic exercise.” The problem with most exercise programs is that the people who need them don’t find them enjoyable and therefore don’t stick with them. Time-efficient workouts, like HIIT, provide an alternative, one that the majority of participants find far more enjoyable, and that avoids the monotony of traditional programs.32 In another study, Astorino debunked the two-thousand-year-old myth that having sex before an athletic competition diminishes performance (it doesn’t).33

How intense does a HIIT workout need to be? You should try to achieve 90 to 95 percent of your maximum heart rate during the short, high-intensity periods. Online tools can help you figure out your maximum heart rate as a function of your age. (A well-known rule of thumb, to subtract your age from the number 220, is misleading for overweight and older populations, so it’s best to talk to your doctor or find an online calculator that takes your weight into account.) If you’re new to all of this, you can buy a heart rate monitor at a sporting goods store or online, and you can wear it on your wrist or across your chest. If you don’t want to invest in equipment before you see if you like it, you’ll know you’ve reached the desired intensity if you can no longer carry on a conversation while running or cycling. You can still run or bike. You just can’t talk.

Wisløff’s research group has also developed an online tool that allows you to enter some physical measurements and a brief lifestyle history to calculate your “fitness age.”34 You might find that your fitness age is younger than your chronological age (keep up the good work) or older than your chronological age (time to get serious about increasing your physical activity).

Regardless of your fitness age, if you are starting from a sedentary lifestyle, you should initiate any new program gradually and with the advice of a physician or personal trainer familiar with older bodies. The risks of hurting yourself unintentionally rise with each decade after sixty—torn rotator cuffs, damaged tendons, falls, and broken bones are all too commonly the price that some older adults pay for being overexuberant. We remember back to when we were kids and would engage in any new activity without thought, moving our bodies in any way that occurred to us, usually with complete and utter impunity. In our minds we are still that limber, flexible kid. We forget that time in our thirties or forties when we got a sprained ankle or hurt back so easily. You might still be physically capable of doing a large number of things, but it’s especially important for older adults to ease into it, to learn how to stretch before and after, and to stay hydrated.

Small Changes, Not Gym Memberships

The story gets better yet. Even the teensiest, tiniest, barely measurable amount of physical activity improves brain function—not as much as the HIIT mentioned previously, but it is significant and it matters.35 The very largest improvements we’ve seen for reducing risks of cardiovascular disease and diabetes, and improving memory, come not from moderately active people who engage in a more systematic and intense program, but from sedentary people who engage in the barest minimum of physical activity—even just getting up and walking a bit.

The figure above comes from a study of more than six thousand British men. The curve shows their mortality rate (death due to all causes on the y-axis) as a function of physical activity level. As you can see, the steepest drop in the curve—showing the most pronounced benefit—is between inactive men and men who had only “occasional” physical activity. And at least in this study, vigorous activity was not associated with any gains above moderate activity. The oldest adults tracked in this particular study were eighty-four.

This concept of minimal activity made a splash in 2018 with a paper published by an international research team led by Kazuya Suwabe from the University of Tsukuba in Japan and Michael Yassa at the University of California, Irvine. They had people engage in a single bout of light physical movement, just ten minutes of pedaling on a stationary bicycle so lightly that it barely raised their heart rates at all.36 A control group sat on the bicycles and didn’t pedal. Afterward, the researchers gave everyone a standard memory test. During a study phase, participants briefly saw a series of pictures of everyday objects, say, a sofa or a tree. During a testing phase, they were then shown either the pictures they had previously seen or pictures that were different but similar. This is a difficult test because it relies on keeping subtle differences active in memory. These are the kinds of distinctions we make every day when remembering, say, that we parked our car on the second floor of a parking structure versus the third, or that the new person we just met is named Ellen and not Elaine, or that, yes, we did take that heart pill at lunchtime.

The participants who engaged in even this minimal physical movement outperformed the couch potatoes (er, stationary bike potatoes) by a substantial amount. The researchers performed the experiment again, but this time, they presented and tested the pictures inside a brain scanner (fMRI). They measured activity and connectivity in the hippocampus, and connectivity in other cortical areas associated with learning and memory. What they noticed was immediate enhancement of these brain regions and connections, simply as a result of this extremely light movement. The brains of the participants who pedaled lightly worked very differently from the brains of those who were stationary—there was more coordinated activity in these essential memory circuits, and the more difficult the memory task, the more coordinated activity they found. Furthermore, the neural enhancement was specific to those regions involved in learning and memory—other brain regions, such as the amygdala, perirhinal cortex, and temporal pole, showed no difference, allowing us to rule out that exercise created a globally higher state of brain arousal.

Prior to this study, it was widely thought that the benefits of exercise were dependent somehow on the body entering a stress response and releasing cortisol. But Suwabe and Yassa measured cortisol in their participants and found no differences—the improvements in both hippocampal activity and connectivity occurred even without a stress response. Further good news is that you don’t have to be physically active over a long period to see benefits. Cognitive benefits show up immediately, and by twelve weeks improvements in cerebral blood flow are evident.37

Movement activities are particularly helpful, indeed essential, for individuals who have a cluster of conditions called metabolic syndrome—increased blood pressure, high blood sugar, excess body fat around the waist, and abnormal cholesterol or triglyceride levels—which substantially increases the risk of heart disease, stroke, and diabetes.

One of the problems with exercise is that, like with dieting, people start out with overly ambitious plans that are difficult to maintain. The majority of people fail to follow through with these plans because they lose interest or find them boring or too difficult to integrate into their daily routines. For those who are out of shape, the thought of going to a gym may be intimidating. It is a fact of the gym industry that a large proportion of people who take out gym memberships end up not using them—this is one of the reasons that so many gyms require that you pay for a year in advance!

Walter Thompson, a kinesiology professor at Georgia State, summarizes:38

We cannot just tell people that they need to exercise more; it does not work. Our work clearly shows that we need to demonstrate lifestyle modifications that can be adopted by most of the population and get away from sending people to gyms. Small changes in behavior, like parking your car in the last row instead of the first row at the grocery store or climbing stairs instead of the elevator, are just two examples.

Richard Friedman at Weill Cornell Medical College extols the virtues of walking for neurocognitive health: “Perhaps it’s the fact that you are constantly bombarded by new stimuli and inputs as you move about, which helps derail linear thinking and encourages a more associated, unfocused thought process.”39

Last August I visited my friends Heather and Len, who, at age sixty-nine, are both physically and mentally very active. We went for a hike in a forest near their house in the Quebec countryside, a hike they do regularly but I had never done before. Actually, calling it a hike is a bit highfalutin. It was really just a walk in nature, on dirt trails. The walk was invigorating, and all of these ideas about embodied cognition, and the words of Scott Grafton, came together for me on this walk. Look at this cell phone photo I took of the path.

A tangle of branches, roots, and rocks, it demands attention to avoid tripping. Every minute of walking requires hundreds of microdecisions about where to place my foot, how much pressure to use when setting my foot down and picking it up again, how to balance myself, how to lift off my foot to move forward to the next step. This rugged terrain wasn’t the half of it. I had to be attentive to avoid getting whacked in the face by low-hanging branches. Birds and critters were all around, and although I didn’t fear that any of them would attack me, I did have to brush away spiders, flies, and mosquitoes, and the occasional three-year-old running up and down the trail with a stick flaying wildly across the path. The number of variables—things that could happen to you—is infinite. You see it in the excitement of your dog. The varied terrain, the people, the vegetation, are all changing. The chance of running into people or things you haven’t encountered before, or haven’t encountered in exactly that way before, adds to the thrill. This was the kind of navigation our brains evolved to perform. This was the kind of embodied cognition that strengthens synapses and rejuvenates hippocampal memory systems, motor-action planning systems, and eye-body coordination. Outdoors, anything can happen. And that’s the most potent way of keeping the brain flexible and active that we have so far discovered. A bustling city street can render some of these same effects, minus the hidden and ancient power of naturescapes to be mentally soothing and stimulating at the same time.

Scottish doctors have begun issuing prescriptions for “rambling and birdwatching.”40 And as journalist Justin Housman says, these prescriptions are being used to treat a wide variety of maladies:

For everything from high blood pressure to diabetes, anxiety, and depression … ailments and diseases can be treated with activities like bird watching, maybe a little kayaking, perhaps combing a beach for shells, even skipping pebbles across a slow moving stream.41

Doctors in Quebec have begun prescribing free visits to the Musée des Beaux-Arts Montreal (Montreal Museum of Fine Arts) for patients suffering from a number of physical and mental health issues, to enjoy the benefits that art can have on one’s health. Walking indoors through a museum (or even a mall) provides a high chance of coming across people and things you haven’t seen before, and the amount of ground you cover can be surprising.

Exercising on a treadmill is good. Walking around the neighborhood is better. Walking in nature is the best. The winter after my colleague slipped on the black ice, I went out and bought crampons—traction cleats—so that I wouldn’t have an excuse not to walk in the long Montreal winters. I will not go gently.