A quick bit I took from reading The Inner Game of Tennis was removing judgment from anything you do. Stop labeling things as "good" and "bad" and simply take them as is. For example, if you miss a shot, many label that as "bad." When you label things as "bad", you become tight. Tightness interferes with the fluidity requried for accurate and quick movement. Relaxation produces smooth movements, and this comes from accepting things "as is." Stop beating yourself up for "mistakes." Rather, don't even label things as "mistakes". Take each action "as is."