In his book Sweat: A History of Exercise, author Bill Hayes explores the history and significance of exercise from ancient times to the present day. He delves into how exercise was once celebrated in Greek and Roman cultures, but was later suppressed by Christianity. Hayes also delves into the personal aspect of exercise, recounting his own experiences with swimming and walking after the death of his partner. He reflects on the physical and mental benefits of exercise and its connection to overall well-being.