Here is a great way to strengthen your core muscles while lying on the floor. This exercise recruits muscles in your abdominals, back and hips to stabilize your spine against the movement of your legs
Lie face up on a flat, level surface. With both legs straight above your hips, move your right leg down to approximately 45 degrees. Reach your right arm overhead, with fingertips touching the floor. Inhale.
On an exhalation, press your navel to your spine as you slowly lower your left leg toward the floor as low as possible without allowing your back to over-arch. Pause for 2 seconds, then raise it up. Throughout this move, be sure to keep your admonial muscles flat with your right leg and arm motionless. Do eight to 12 repetitions, then switch legs and arms and repeat.
Voight is the creator of a line of fitness DVDs, including "Full Body Stretch" and "Ballet BodySculpt."