* Dopamine is not the only chemical that influences your habits. Every behavior involves multiple brain regions and neurochemicals, and anyone who claims that “habits are all about dopamine” is skipping over major portions of the process. It is just one of the important role players in habit formation. However, I will single out the dopamine circuit in this chapter because it provides a window into the biological underpinnings of desire, craving, and motivation that are behind every habit.