Breathe with your whole body
Originally, humans used their entire body to breathe. Since the body was in a relaxed state, it was possible to produce energy through breathing without exerting much effort. However, for one reason or another, the stomach becomes rigid and the original body is distorted, resulting in a vicious cycle of increased energy consumption and increased fatigue. It's been like that for decades.
You should now return to your original breathing. You should breathe through your entire body again. This relaxes the body and enlarges the torso. However, even if the torso grows through relaxation, the stiff muscles and nerves holding the liver cannot catch up. It means you can't go back to normal. Naturally, fatigue substances are not properly disposed of. The liver becomes overworked due to the suddenly increased fatigue substances, and feels more fatigued than before relaxation. At this time, you need wisdom to take a break and restore your body and liver. You have to let go of your mind and take a deep breath. Reducing energy consumption when breathing to a minimum, or reducing fatigue substances to come out is a way to slowly age the body.