Try not to lose...

That's commonly heard at my weekly tennis clinic when Mark has us doing drills. He'll put half the class on one side of the net and the other half on the other side and he'll tell us to play competitively and then he'll tell us try not to lose. Which is a different way of saying try to win. And while "try not to lose" and "try to win" are essentially the same thing, you want to win and not losing means winning, it's still a different mindset.

It's actually pretty easy to beat yourself by trying to overpower your opponent and then missing the final shot and giving away the win. Trying not to lose is something I need to work on.