Lie down on your back with your knees over your hips and bent to 90 degrees. Reach both arms straight over your shoulders to the ceiling. This is your starting position.
Take a deep breath in, and as you exhale, engage your core.
Place your right hand on the top of your left thigh, and press together until you feel your core shake. Lower your left arm and right leg so they are hovering just above the floor. Do not let your back arch.
Hold for six to 10 seconds while exhaling, then reset to center before switching sides. This counts as one rep.