There is a quote from "The Life Giving Sword" by Yagyu Munenori, a famous Japanese swordsman. He wrote (tranlation by William Scott Wilson):
When you begin to study, there is something in your mind; you are obstructed by that thing, and it becomes difficult to do anything at all. If you can clear from your mind those things you have learned, they too will become nothing; and when you perform the techniques of the various Ways, the techniques will come easily regardless of what you have learned and without being contrary to it. When you perform an action you will be in harmony with what you have learned, without even being aware of it. ...
When you have run the length of various practices and none of those practices remain in your mind, that very lack of mind itself is the heart of 'all things.' When you have exhaustively learned the various practices and techniques and made great effort in disciplined training, there will be action in your arms, legs, and body but none in your mind; you will have distanced yourself from training, but will not be in opposition to it, and you will have freedom in whatever techniques you perform. You yourself will be unaware of where your mind is, and neither demons nor heresies will be able to find it. Training is done for the purpose of reaching this state. With successful training, training falls away.
This is probably one of my favorite quotations with respect to training and developing skill at anything you do. It was written with respect to swordsmanship and is especially relevant to Tai Chi and other martial arts. Even when we practice Tai Chi solely for the wonderful health benefits it can bring, this truth applies. We begin in a fog of confusion but disciplined training will dissipate that fog and eventually lead to a light of clarity beneath which even the shadow of discipline and training disappear. I am still seeking that light.