Reverse Crunch

There are two ways to do this exercise. Lying on your back, you are using your lower abs to lift your hips and tailbone off of the ground. You can keep your neck and chest on the ground. The more difficult move involves extending your legs out straight without touching the ground, bringing them back to your chest and then lifting your hips/tailbone off of the ground. You can support your neck and shoulders off the ground with your hands.

If you are not extending your legs, make sure you are not "bobbing" your knees up and down to get momentum to lift your hips. Use your abs!