Side-center-side sit-ups are a great start if your abs are your problem area. These will target your stomach muscles, and work your waist. Just remember, if you do not feel this exercise in your stomach muscles, and feel it in your arms or neck, you are not doing it properly. Control your movements and do not let your shoulders touch the ground.
Step 1. Lie on your back with your feet flat, knees bent. Place your hands behind your head.
Step 2. Using your stomach muscles, raise your upper body, twisting toward your left leg.
Step 3. Return to starting position, and in a fluid motion, lift your upper body to the center.