The belly is a little fleshy, so it's easier to practice. Besides, you should combine relaxation with devotion. Take the navel as the boundary, separate the lower abdomen from the stomach, and then move the internal qi up and down with your own breath. When the lower abdomen is retracted, the stomach is protruding, and vice versa! Anyway, it is just a convergence of a bulge, and finally slowly connected, it looks like a wave. That's how I practice. To practice belly flipping, we must first find the "layering" of the stomach. Upper part: middle part of the chest: lower part of the stomach: when the lower abdomen rolls, it is most important to suck the whole abdomen with abdominal breathing (abdominal exhalation). Note: when exhaling by abdominal breathing, exhale in the order of closing the chest, stomach and abdomen first. When inhaling again, inhale in the order of chest inhalation-stomach inhalation-lower abdomen inhalation. Maybe I didn't master the movements and feelings well at first. Take your time. With the strengthening of muscle control, you will definitely make a beautiful belly roll in the near future! !