The air crunch is probably the most well known exercise out there. It's really easy to do and if you have never done the exercise before, you will instantly feel your abdominal muscles working. Lie on your back with your feet resting on a bench and your knees bent at a 90 degree angle. You can also place them flat on the floor as I'm doing here in the video. With your hands lightly on either side of your head or neck, begin to roll your shoulders off the floor. They should come up off the floor only a few inches while your lower back should remain on the floor.

At the top of the motion contract your abdominals hard to maintain the contraction for a second. Then slowly lower to the original position. You want to keep your lower back against the floor in your hips straight doing the entire exercise. Focus on slow and controlled movements. Don't cheat yourself by swinging your upper body