Joggers get started because they hear it’s good for their heart and peace of mind. Then they get interested in maybe going a little faster, doing a certain number of miles a day, completing a certain course. When the course gets long enough, pain sets in, and the question is whether you’re going to believe in your pain and quit or keep on going. If you keep on going, you realize how subjective pain is—you learn that sometimes it’s telling you to watch out for your body but that at other times it’s just complaining. And then you learn how to deal with the complaints—you move your attention away from the pain and keep on running.