Very effective. Do 30 exercises every day and increase by 65,438+00 per week. By the end of four months, the original quantity can be kept unchanged. It will be difficult at first 1 month, but as long as you can persist for four months, you can see obvious results. However, sit-ups should be a compulsory course for you every day like eating and sleeping. If you stop, you will rebound badly. (All the above are personal experiences. )