No doubt about it -- exercise helps circulation and can give you a healthy glow. But for your skin's sake, you ought to walk for exercise and not run.

When you pound the pavement, the force of your body jostling can cause collagen to break down, which can lead to sagging skin, says dermatologist Dennis Gross of NYC. Hey, running is not so great for your knees either. I guess walking is the way to go -- although I don't plan to abandon the run just yet. How about you?

(via In Style magazine, August 2008)

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