First, you can do sit-ups. Sit-ups are mainly aimed at the upper part of thin abdomen. You can do 4 to 5 groups every day, with 20 in each group. You can do less at first, and you can do 3 or 4 groups. After a long time, you can see very satisfactory results by slowly increasing the quantity. You must insist on doing it.

Second, you can do leg bending exercise, that is, exercise the lower part of the abdomen. You can do 3 to 4 groups every day, each group 10. Put your legs outside the bed and pay attention to lying on your back with the upper part of your ass. Lift your legs in a straight line with your body, and then slowly lift your legs up until your legs are at 90 degrees to your body. You don't need to do it too fast. You can stick to it slowly.

Third, you can twist your waist, you can do it standing, you can twist it left and right, you can twist it 60 times to both sides, and you can see the effect soon if you persist in exercise.