"Yin Pingyang secret, the spirit is mainly cure. Yin and Yang are separated and refined. " This is an incisive description of human physiological function in Su Wen's Tong Qi Tian Lun. It is believed that the normal life activities of human body are the result of harmony between yin and yang.

Maintaining the balance of yin and yang in human body is the basic rule of keeping healthy and prolonging life. The reason why people get sick is a reflection of the long-term imbalance between yin and yang. The purpose of doctor's treatment is to readjust the unbalanced yin and yang into relatively balanced yin and yang. Health care involves many aspects of the balance between yin and yang. Material life is manifested in food, clothing, housing, transportation and use. In terms of spiritual life, it is manifested in sex, emotion and mind. None can be surplus, and none can be insufficient. Grasp the appropriate degree, which is the best degree of balance between yin and yang. Therefore, we should pursue the balance of yin and yang in all aspects of life in order to have a healthy body.