From Huangdi Neijing: "Those who know the ancient times, yin and yang are in harmony, several strokes are in harmony, diet is in harmony, and life is not impetuous, so they can be in harmony with God and die at the age of 100."

"The law is based on Yin and Yang, and on the number of skills", which is the general principle of health preservation in Huangdi Neijing, and its essential meaning is to live according to the laws of nature.