On every televised professional tennis match, the commentators regale you with statistics on how many unforced errors the players make. But just what is an unforced error? Many people in tennis don’t even believe there’s any such thing. They reason that on every shot, your opponent puts spin, pace and direction on the ball. He is trying to force you into missing the shot, to pressure you or psyche you into committing and error. So you never can say that your opponent didn’t have an influence on your return on any given shot. I don’t believe that. As a tennis player, you have achieved a certain level of proficiency in the game. Therefore, no matter what your opponent is trying to do, if the ball’s flight time doesn’t challenge you, if the ball’s spin doesn’t challenge you, or the position on the court doesn’t challenge you, then indeed you should make the shot. If you miss, that’s an unforced error.