That's why in acting, when given a choice, it's stronger to play your actions as if you were doing it for the first time.  Easier said than done.  But the best actors and the best tennis players are able to do this:  to live in the moment, with no history or future to worry about.  While this behavior would be absolutely irresponsible in real life, in the context of sports or the performing arts, it is the best way to delivery a strong performance.  Again, easier said than done.  After today's loss to Novak Djokovic at the Wimbledon Championships final, Rafael Nadal admitted that his four straight prior loses to Djokovic weighed on his mind during his match today.  (This comes from one of the greatest tennis players of all time, who is renowned for his ability to compartmentalize his game and play each point as if it were the only one that mattered.)  Today, Nadal looked past the moment at hand, and that made the difference in his result today.  So, when you're on stage - just as you wouldn't get ahead of yourself on match point or carry the disappointment of a bad line call against you from the point before - live in the moment and that moment will be more enjoyable for you, your partner, and the audience.