As far as the human body is concerned, yin and yang are integrated, opposed, mutually rooted, ebbed and flowed, and transformed.

The human body is sick because of the imbalance of yin and yang. The essence of treatment is to help patients adjust yin and yang and achieve the balance of yin and yang. If a person has a balance of yin and yang, his body will naturally be healthy.

Yang Qi is opposite to Yin Qi. In terms of function and form, yang refers to function; As far as the function of zang-fu organs is concerned, it refers to the qi of six fu-organs; As far as the spirit of military camp guards is concerned, it refers to the spirit of guards; As far as the direction and nature of exercise are concerned, what is extroverted, upward, vigorous, enhanced and light is Yang. Su Wen Angry Days: "If the sun is Yang, if the sky and the sun lose their places, they will lose their lives." "Sun be the spirit, essence is resting to restore energy, and softness is nourishing tendons.

Yin Qi refers to matter; As far as the function of viscera is concerned, the qi of five zang-organs is yin; As far as qi is concerned, it is yin; In terms of the direction and nature of movement, downward, inhibition, weakening and turbidity are Yin Qi.

Protecting yang qi and benefiting yin essence. Maintaining Yang Qi and nourishing yin essence are important principles of TCM health preservation and rehabilitation. Everything depends on Yang for its birth and Yang for its death. A person's growth is dominated by Yang, and the generation of essence, blood and body fluid is transformed by Yang. Therefore, "Yang is strong and longevity, while Yang is weak and death". But people who are good at keeping in good health must cherish their essence. Because essence is full of energy, energy is full of spirit, and spirit is full of health.