Sit on the floor with your hands directly next to your hips, fingers facing your feet.
Keeping your arms and legs straight, push your hips up until your body is in a straight line called reverse plank.
While holding this, lift your left leg and drive your knee in toward your chest. Return your leg back to the reverse plank position, and repeat on the other side.
Do as many knee drives as you can for 40 seconds. Rest for 10.
