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The best tool for a strong chest: Medicine ball

Strong-chest move: Roll-the-Ball with Uneven Push-Up

Here's why: "Stabilizing yourself on the ball—and rolling it back and forth—requires you to engage all of your chest muscles, including the smaller ones that often get bypassed," McGee explains. "And a medicine ball is the perfect size for push-ups." The unevenness of the push-up also helps balance out your strength by not allowing your stronger side to compensate for your weaker one. Plus, the position targets the underside of your chest, helping give the girls a lift.

Next: How-to: Roll-the-Ball with Uneven Push-Up