Lie flat, put your hands on your head, lift your thighs and calves at 90 degrees, lift your left and right thighs in turn, and lift your legs 30 times at the same time. Remember that you mainly rely on tightening the strength of your abdomen. You can rest 10 and 15 seconds after you finish. Lie flat and lift your legs, put your hands behind your head, and then lift your left and right legs in turn, preferably perpendicular to the ground, for 30 seconds. Sit-ups on the opposite side lie on the ground in a sit-up position, then bend your legs, put your hands on your chest, and press your head close to your legs with the strength of your abdomen for 30 times, and end the rest.