Hold your breath. After fully inhaling, hold your breath instantly, go all out, buckle your teeth, scratch your toes and tighten your anus. Every muscle of the whole body should be tightened, including the neck, the whole arm, the chest and abdomen, the buttocks, the thighs and the ankles, in short; The whole body should be nervous, so you can check it with your mind. The body can see that there is no tension, especially abdominal tension, which lasts for 3-5 seconds. Holding one's breath is also a common breathing method in hard qigong, which is unique to China, and is often accompanied by hum, ha and hey.