Yashmeen Manak, physical instructor, performs reverse crunch that is necessary for stronger, sleeker and perfectly toned stomach. Unlike regular crunches that work for the upper body, reverse crunches are for lower body. Lie on the floor with your back straight and keep your palms under your hips. Lift your legs up with your feet in the air and knees bent at 90-degree angle. To start reverse crunch, slowly roll your hips off the floor with your knees coming closer to your face and your legs and feet a few feet higher. Hold this position for 4-5 seconds. Exhale when you roll upward and inhale while returning to the beginning point. Slowly lower your hips back to the floor.