A tonic

Tai chi is not going to fix you up.
It was never intended (or designed) to be something employed for repair.
At best, it may be seen as a tonic.

A tonic is a medicine taken daily in order to maintain and invigorate the body.
It may significantly improve your health.
However, you should take note of the small print, the conditions of use:

1. It must be administered every day 
2. When you stop taking it, the health benefits go away

This is something to really think about. Re-read the paragraph if you need to.