The key to success in endurance endeavors, he said, "is learning to ignore that signal and replace it with something else."
Mental training begins with the very first step of an exercise program, especially for people who are athletic novices, said Greg Whyte, an endurance athlete, coach and cardiovascular physiologist at Liverpool John Moores University in the U.K. He has successfully trained British celebrities to complete long-distance feats, like waterskiing across the English Channel and running 43 marathons in 50 days.
First comes commitment to a goal. Then comes confidence that builds gradually as an athlete learns to cope with ever-longer bouts of arduous exercise.
One of the most common and successful strategies for enduring discomfort is to compartmentalize an overall goal into much smaller goals.
Ironman competitors, for example, do well to avoid dwelling on the overwhelming idea of 12 long hours of swimming, biking and running. Instead, it can be helpful to think of each leg separately and from there, to break down each sport into manageable increments of time or numbers of strokes, pedals and footsteps.