In ancient China, life span was called "tiannian", which means "the life span endowed by Heaven for existence in the world." Ancient medical professionals believed that the normal human life span is 100 years to 120 years. According to the biological laws, the life span of mammary animals is 5 times to 7 times than that of the period of growth. The life span of human is calculated according to the time of dentition of the last tooth (at the age of 20 to 25). Accordingly, the life span of human should be 120 or so. However, due to natural and man-made calamities, poverty and diseases, most people suffer from shorter life and cannot reach the normal life expectancy. The average life span of the Chinese is about 70, 50 years shorter or so theoretically. More information, please read TCM Gynecological Pathogenesis.

Life span is determined by the human health conditions while the main factors affecting health are ageing and diseases. Accordingly, preserving and restoring health are the essential requirements for longevity.

Inspecting "spirit" can judge whether the human body is healthy or not. The signs of "having spirit" are as follows: the general appearance is sturdy, neither fat nor thin; the beard and hair are black, bright and lustrous; the complexion is ruddy with delightful expression; the eyes are expressive and full of vividness; the respiration is calm and neither rapid nor slow； the appetite is good with three meals deliciously eaten; the teeth are hard and firm without caries and injury; the sense of hearing is acute without tinnitus; the voice is loud and clear with long breath; the waist and legs are flexible without pain and soreness; the urination and defecation are smooth with normal discharges; the tongue is red with thin fur while the pulse is even and slow. More information, please read Gynecological Invigorating the Kidney.

The above discussion includes two parts of physiological and psychological health states. In fact, TCM has held that psychological health is as important as physiological health since ancient times. The theory of "seven emotions" in the etiology requires emotional regulation and spiritual happiness. This is also the external manifestation of good visceral functions.