Start by lying on your back, with your legs flat against the floor and your arms at your side. Hover your feet an inch or two above the floor and sweep them out to the side and back to center, hovering the entire time. At the same time, you move your legs, sweep your arms out from your side in a circular motion up above your head, keeping them close to the floor. You want to keep your stomach muscles engaged throughout the exercise and your lower back firm against the floor. Then return your arms and feet back to your side and center at the same time. Your motion simulates making a snow angel, except you want to focus on keeping your arms and legs from ever touching the floor.