Calculations based on the Harvard Alumni Study, suggest that men who work out and maintain physical exercise regularly can gain about two hours of life expectancy for each hour of exercise.

Over the course of a lifetime, that adds up to about two extra years. Maximum benefit does require regular exercise over the years.

Luckily it doesn't have to mean a trip to the gym every day. Analysts say that at least 30 minutes of brisk walking every day will go a long way toward enhancing your health.

"Exercise is not the fountain of youth," says Dr. Harvey Simon, editor in chief of Harvard Men's Health Watch, "but it is a good long drink of vitality, especially as part of a comprehensive program that includes aerobic exercise, strength training, and stretching."