One key to running your best 10K is to not run the first mile at 5K pace. For most runners, that’s a difference of only 10 to 15 seconds per mile. But that’s a significant difference in effort level. If you’re already breathing every second step in the second mile of a 10K, you’ve gone out too fast. To keep the race from becoming a complete disaster, back off for a few minutes to allow your breathing to slow, then pick up the pace again.