The key to bodyweight exercise is mixing it up. Challenge yourself. If you're not sore the next day, you didn't work out hard enough. "When you push yourself, you'll be building muscle, increasing bone density, strengthening ligaments, and burning calories for up to 36 hours after your workout," says Mark Lauren, author of 'You Are Your Own Gym.' When push-ups become too easy, switch to a different grip – wide, narrow, or staggered hands – or pause during the motion. Try one set on an incline, the next on a decline, and the next with one hand on a basketball. For all of the exercises below, aim for three sets of 10 reps unless noted otherwise. Time yourself and try to do them more quickly the next time around. If you can't finish a set, complete it with the easier version.
The No-Weights Workout: Planks
Squeeze your glutes and stomach. Press elbows to the floor to activate shoulder muscles.
Make it Hard
From push-up position, walk your hands until your arms are nearly straight. Plank on fingertips and toes.
Credit: Photograph by John Loomis
From push-up position, raise one arm and the opposite leg to parallel with your back. Hold for one minute.