Lie on your back with your feet about 12 inches from your butt. Place your hands slightly out to the side with your palms facing up.
Press your heels into the ground and lift your pelvis up until your knees, pelvis, and shoulders form a straight line.
Hold this position as you lift your right knee toward your chest, until your hip is at a 90-degree angle. Return your heel to the floor and repeat with the left leg.
Continue alternating legs for 40 seconds. Make sure to keep your core engaged to prevent your pelvis from sagging down.