Beautiful abdominal muscles depend on three elements: a reasonable diet, aerobic training and regular abdominal muscle training. Only by combining the three harmoniously can we have the abdominal muscles we dream of. Introduce three ways to exercise abdominal muscles for your reference. 1. Knee down and abdomen in. 2. Lift your legs. Group three. Fifteen times. Twice a day. Rest for 30 seconds between groups. Sit-ups can be done twice a day, once in three groups, 30 to 50 in a group, and rest for one minute between groups. If you exercise at this intensity and amount of exercise, you will have a preliminary effect in half a month.