You are already very thin. If you want to keep fit, the easiest way is sit-ups. If you feel that the intensity of simple sit-ups is low, you can buy a supine board (around 130 yuan, which can be found on a treasure) to exercise at home, but you should keep the standard when doing it. Don't put your hand on your head, but gently put your finger on your ear, so you won't borrow money. Get up quickly, and then lie flat as slowly as possible when you fall. Three times a day, five groups each time, three in each group, and gradually increase the intensity. Secondly, the abdominal wheel is like a stroller, which can be exercised at home, but it is very difficult to make. I haven't insisted for months. You can try it if you are interested. Third, this is what I learned from the boxing team. After running every day, hanging upside down on the parallel bars (have you seen this), your body naturally sags. I grab some heavy things (sandbags, bricks and the like) with my hands, then bend down and do as much as I can. This method is stronger and more effective.

The above three methods are the simplest and most practical ones that I have personally verified. The key is to do it anytime and anywhere to facilitate exercise. Pay and return are in direct proportion. Although it is a hard process, you can also feel the joy of taking control of yourself after success. Wish you success! The above is my personal experience and understanding, hoping to help you.