Lie flat on your back on a mat and raise both legs straight up toward the ceiling.
With a slow and controlled motion, lower your left leg until it is around 6 inches above the floor.
Contract your abdominal muscles to perform a crunch toward your raised leg.
Raise your left leg while lowering your right leg until it is around 6 inches above the floor. Crunch toward your raised leg. Repeat for 10 repetitions.