According to Consumer's Union, it is the beginners that give up using the equipment more than people who already enjoy an active lifestyle. In conclusion... It is also important to note, that for many people, a flat stomach is not in their genetics, even if they are computerized. Abdominal Exercises & Equipment Gravity resistance Lift your legs straight up above your head and bend your knees slightly. Squeeze your abdominal muscles and bend your knees slightly. Squeeze your abdominal muscles and then lift your torso up off the mat toward your knees. Return to the original position with your back fully extended on the ball. Tighten your abdominal muscles and raise your trunk off the ball to about a 30-degree angle. Return to the original position with your back firmly against the padding. You should have the Roman Chair set high enough that your legs dangle straight down when you are in position. Then slowly bring your knees toward your chest as far as you can go and hold for a few seconds before extending