"Stop! Look! Listen! It's time for The Jack LaLanne Show. " So began Jack LaLanne's daily exercise program, syndicated on television stations nationwide from 1959 to 1985. The muscular man in the jumpsuit led simple exercises, often of his own invention, and urged his audience along with the enthusiasm of an evangelist: "If your back porch is draggin' and your shoulders are saggin' and you have no pep in your step, it's time for a change!" In this age of fitness gurus, personal trainers, and exercise videos devoted specifically to achieving "buns of steel," it seems impossible to imagine a time without health clubs, when weight training and aerobic exercise were viewed by doctors as extreme and potentially dangerous activities. However, in 1936, when Jack LaLanne opened the first fitness club in the United States, many considered him a kook and a fanatic. Though he is arguably a...