I really loved Kung Fu Panda 2, not only for its great comedy and what not, but for the hidden messages and gems. The main theme was about Po finding "inner peace" in order to defeat not only his physical adversary, but his mental one as well. As musicians, I think we often perceive people as being critical or judgmental about our performance, or lack thereof, giving us more anxiety and stress. Finding a way to counter or remove that idea from our psyche will inevitably give us more freedom not only in our playing but in our daily lives. While this concept is very much tied to "the ego" and how we perceive ourselves, I talk about it here because of the physical response it creates.
When we act out of fear, we lose conscious control of our actions, making the outcome often undesirable. If we act out of trying to impress, the outcome becomes tainted with almost a "showboating" feeling. If however the action is from a place of rest, where your mind and body are at peace, then the process towards the outcome is clean and clear, able to be shaped to whatever is needed. It's not, "Oh, it's so soft so I have to be careful not to play too loud." It's, "Let me just play soft." Don't add unnecessary adjectives to your process. Soft is soft, not scary because it's soft and you have to lower your sticks and what not.
So, think a lot simpler about what you're doing and the intentions of those actions. Is it out of fear, necessity, obligation, self gratification, or for its own sake? If we can get clear about those, we probably can find the underlying problems with not only our performance on stage, but our performance in life.