Did you know that physically fit people are 40% less likely to catch a cold? True, according to a recent study. Why? Exercise motivates your infection-fighting cells to do their job - this study, from the British Journal of Sports Medicine, found benefits from 20 minutes of exercise five days a week, but a little more wouldn't hurt you! Just be careful - extreme exercise does suppress your immune system . . . "happy medium" is the name of this game.