Neijing said: "Yang is the foundation of life. If the sky is in harmony with the sun, it will lose its life if it does not show its strength." . Whether the yang is sufficient or not is closely related to human aging, disease occurrence and even death. If we count yang as 100, then from birth to death, it is the process from 100 to zero, that is, from birth to death, from health to disease, it is the process of eliminating yang. Therefore, it is important to maintain and enhance the yang. Strong and dense yang, harmony between ying and Wei, can defend against external evils: strong spleen yang can transport subtle, and sufficient kidney yang can promote the whole body's qi and blood circulation, strengthen the five internal organs and prolong life. This is the health-preserving realm of "Yang essence is strong for thousands of years" and "Yang essence is strong for thousands of years".