It is incurable. In other words, Zhu is saying that emotional health is the root of breast diseases. With proper diet and keeping the spirit calm, serious breast disease is treatable or, better yet, preventable. While we all know what to eat to support health and what other healthy lifestyle choices are, it never hurts to go over them again. We also know that we should eat lots of leafy greens and organic foods to limit chemical xenoestrogens, etc.
Exercise controls stress by letting off steam, just like releasing the valve on a pressure cooker.
It stimulates the lungs, which helps keep the liver in check and encourages the smooth and harmonious flow of qi. Exercise also helps prevent blood stasis by keeping qi and blood flowing smoothly. The other way to get rid of the pressure in a pressure cooker is by turning off the heat. This is analogous to relaxation therapy in our lives. Instead of blowing off steam through exercise, we can turn off the heat.