One of the simplest ways to protect your body from breakdown: Make sure your right and left sides are equally strong. "Everybody has a dominant side that's naturally stronger," says Tracey Mallett, a personal trainer in Los Angeles. But if the balance gets too out of whack, your strong side has to compensate for your weak side--and that can result in overuse injuries.

This quickie routine from Mallett works your arms and legs; but just as important, it works your core, which is what will help your left and right sides do equal work. Include these exercises in your strength routine two nonconsecutive days a week.