For one workout, do 3 sets of 12 to 15 reps per side. For your next workout, do 4 sets of 6 to 8 reps per side.
How to do it: Rest your head and shoulders on a weight bench, arms open to the sides, palms facing up. Walk your legs out until your knees are bent at about 90 degrees and your feet are positioned directly below your knees. Lift your hips so that your body makes a straight line from knees to nose.
Keeping your right knee bent at 90 degrees, lift it above your hip. Keeping your right leg lifted, lower your hips towards the floor, and then press hips back up through your left heel. That's one rep. You can make this move more difficult by adding weight—try holding a weighted bar across your hips.
