If you want to exercise thin belly, you can lie on your back at night, put your legs together, put your hands on your sides naturally, and slowly straighten your legs up with the strength of your hands and abdomen until they are at right angles to the ground. Or lie on your back with your legs open shoulder width. Keep your arms straight and elbows close to your ears. Lift the left leg and right hand respectively, straighten the upper body, and let the right hand touch the toes of the left leg.