I Did This 5-Move Ab Workout, and Naturally, My Abs Were Trembling Right Away

Only do this move on your final round.

• Begin in a seated position. Bend your knees, and lift your feet off the floor, balancing on your bottom.
• Keep the spine long, and straighten your legs as much as you can without rounding your back. If this is too hard, keep your knees bent — you're still working your core.
• Hold for 30 seconds.