What is the main conflict in Born to Run: A Hidden Tribe, Superathletes, and the Greatest Race the World Has Never Seen by Christopher McDougall?

The main conflict in McDougall's book, Born to Run: A Hidden Tribe, Superathletes, and the Greatest Race the World Has Never Seen, was the fact that the author enjoyed running, but his body was giving out on him. After visiting specialists to determine the source of the pain in his foot, he was told that running was not natural for the body and that he would likely need cortisone shots if he wanted to continue to run. However, he might want to consider stopping his running. Specialists pointed out that many people were injured while running and the body just was not made for all the pressure put on the knees or the pounding on the feet.