Exercise's anti-gravity effect on your body provides more than enough incentive to hit the gym (hello, perky posterior!). But it only works if you do it correctly—too much of one thing and not enough of another can actually add years to your body.
We talked to the pros to single out the most common exercise habits that age you, and what to do instead.
Mistake: You Never Take a Break
If you're tired all the time and feel achy and sore, you may not be allowing your body enough time to heal between workouts, which can age you, says John Higgins, MD, associate professor of medicine at The University of Texas Health Science Center at Houston and director of exercise physiology at Memorial Hermann-Texas Medical Center.
"In your teens and 20s, it took approximately 18 hours to repair muscle fibers affected by a workout, but this increases to 36 hours in your 40s or older," he says. Using those same muscles before they're completely recovered can trigger inflammation. "Workouts become more difficult, your immune system may not function as efficiently, and you may have trouble sleeping," says Dr. Higgins.
The fix: Take enough time between workouts, and allow at least one whole day for rest per week where you do nothing more than stretching or light yoga (these gentle yoga poses are a great place to start!).
More: How Yoga Detoxes and Restores the Body
Mistake: You Focus Only on High Intensity
It's easy to understand why you'd be drawn to high-intensity interval training (HIIT): It burns tons of calories in less time, and the burn continues even after you've finished exercising. But if that's all you do, you're putting yourself at a higher risk of injuries and wear and tear on your body, says Dr. Higgins. In fact, the popularity of these high-intensity workouts has led to an increase in rhabdomyolysis, a breakdown of muscle fibers so severe it can result in kidney damage and even death. "Though still rare, rhabdo can affect other body organs as well, especially if you allow yourself to become dehydrated," says Dr. Higgins.
The fix: Allow yourself a minimum of 48 hours of recovery time after a HIIT workout or after intense programs like CrossFit.