Simply explain, regulating body breathing means regulating and controlling your breathing, taking a deep breath as long as possible and relaxing your whole body. Focus on breathing. Eliminate all other interference. There are many ways to sit still. You can choose what you are more acceptable to. The requirements for the environment are simple, not to be disturbed by the outside world, to keep the air ventilated and the light soft. The best time is before going to bed at night and just getting up in the morning. Skilled people who sit still only need to sleep for 3-5 hours every day. Can improve the quality of sleep very well. If you practice skillfully, you can take the place of sleeping, but there are few such people unless you have great perseverance and interest. I used to know in Baidu that there was a sit-in article by Mr. nan huaijin, which explained it very well and thoroughly. Later, it may be deleted for too long. Sorry, if you are interested, you can download some e-books online and have a look. You can leave me a message if you have any questions! We can discuss it with you. Wish you a happy life!