Centering and rooting are two key elements in practicing Tai Chi and Push Hands. Even if you practice Tai Chi only for improving health, and do not have intention to get into combating, it is essential to understand the importance of centering and rooting. They are the basic elements to insure proper Qi flow.
Tai Chi is a set of movements based on marshal arts. It is designed to give people templates or drills for applications. It trains the body to follow certain routine movements to deal with certain situation. The essence of Tai Chi vs. other type of hard marshal arts is that it suggests people not to attack first. But once defending action is taken, act fast and smart by using internal power (Qi). Centering and rooting are the two things we practice to accumulate the Qi.
Once the Qi is accumulated, it can be used to strengthen ourselves, to improve energy level, and to release pain. It is a natural and effective way of healing.