T’ai chi is a moving Qigong. Each posture is said to send the ch’i to various parts of the body in order of importance. Each movement is said to activate the twelve main acupuncture meridians and thus give the whole body a healthy workout. T’ai chi is mainly preventive but will cure many diseases or body disorders over a long period of time. Usually I will either send a sick
person to our acupuncturist or treat the ailment with a more specific Qigong exercise to have a more immediate effect. Then I give T'ai chi to stop the disease coming back.

The way in which Tai-chi postures work to heal the body is to cause the ch’i to travel along certain acupuncture meridians to perform certain work. This work is to do with the martial art of T'ai chi.
If we imagine that we are performing certain martial techniques, for instance pushing someone over, and if we have understood the criteria for the practice of T'ai chi, the ch’i or energy will flow along the meridians in order to reach its goal of pushing.

Before the ch’i has reached its goal it must pass through certain organs and is able to heal those organs as it passes. What we do is fool the mind into doing a task when there really isn’t a task to be done. If we really had to push someone over then we would create tension in order to do it, and the ch’i would be blocked. After many years of practice we learn to work and still have the ch’i flow to all parts. This is because T'ai chi has a rather unique training method to teach us to perform tasks while still remaining relaxed. This exercise is called toi-sau or pushing hands. It involves two people using certain pushing and defending techniques to try and push without using brute force (tension) and to defend themselves without using tension. In this way the ch
’i is turned into jing, a sort of purified ch’i which can be used for work.

From - Buddhist Meditation - Contemplation of the Mind