In the midpoint of life, I found myself lost, in a dark place. So I tried to figure out exactly how many miles I had run to get there. Just before turning 40, NPR's Peter Sagal left his sedentary life behind, and embraced running. With humor and insight, Sagal reflects here on attempting to "quiet his colon" while taking a lap in his neighborhood, running a winter charity race in his underwear, volunteering as a guide for visually impaired runners, and taking part in the fateful 2013 Boston Marathon. Exploring the subculture, Sagal also comments on the similarities between endurance sports and sadomasochism, and recounts some of the odd but extraordinary bonds created among strangers and friends sharing the road.