When you perform the movements of t'ai chi, it is like you are watering a plant.  When a plant receives water, it is able to photosynthesize sunlight into energy and grow. So it is with t'ai chi.  It is like an essential element. When you move in the most integrated and relaxed way possible, it is a tonic for the whole body--allowing you to develop your own vitality. As you perform the postures of t'ai chi, your muscles relax and your body comes into a natural alignment. Your energy begins to circulate more freely and this can bring into a greater balance. 

But how do you know your movement is correct and can bring you these benefits?  It is actually the martial arts aspect of t'ai chi that allows us to know we are performing the movements correctly. The principles of t'ai chi tell us that we should move in the most relaxed and integrated fashion possible. We can discern whether we are moving this way more easily if we have an outside perspective. For example, we can test our push movement by trying to push something in a relaxed and integrated way.  As we are pushing, we may feel a buildup of tension in our shoulders and a resulting lack of integration to the back.  Or we may feel a little pressure in the lower back resulting in a lack of integration to the legs.  As we feel these tensions, we can release them.

The martial application of the movement allows us to get an external feedback so that we can see if what we are doing both accomplishes the function and stays within the principles of relaxation and itegration.  Whether or not we actually fight, it is the combination of functionality and principles that provide both healing and martial benefits.