If you want a slimmer or more toned down abdomen, then this move is perfect for you. For this, you will need a firm, flat and carpeted surface. Start with lying on your back with your legs together and straightened. Slowly stretch your legs up while propping your lower back on your arms. Maintain this position for 30-60 seconds. This exercise stretches your legs, hips, and back. To return back down, bend your legs, and this will lower you back down.