Do this exercise slowly. Try to keep your body straight at all times, and do not let one hip drop lower than the other.

1. Lie on your stomach, resting your upper body on your forearms.
2. Tighten your belly muscles by pulling your belly button in toward your spine.
3. Keeping your knees on the floor, press down with your forearms to lift your upper body off the floor.
4. Hold for about 6 seconds, then lower your body to the floor. Rest for up to 10 seconds.
5. Repeat 8 to 12 times.
6. Over time, work up to holding for 15 to 30 seconds each time.
7. If this exercise is easy to do with your knees on the floor, try doing this exercise with your knees and legs straight, supported by your toes on the floor.