Great tennis players are unfazed by failure in the moment, they wait until the match is over to let emotions set in. 

Getting accustomed to failure and learning how to handle it well is what success is built upon.

If you've won the first handful of points or games, well done, but the match isn't over until you win two or three sets. Momentum can change on a dime - your opponent is adjusting their game as much as you are to see what is effective.

You must stay engaged in your performance regardless of how far ahead you are because you never know when circumstances will shift.

Your confidence can't be at the whims of every point, game or set lost. Knowing how to remain calm, not feeling discouraged or frustrated throughout a match can make all the difference. 

Nothing is more unnerving than playing someone who can not be discouraged, and refuses to lose no matter how far behind they get.

Staying the course, and absolutely refusing to go down is part of what makes tennis so exciting: you watch people regain confidence in real-time.

Sometimes you'll come out on top simply because you refused to throw in the towel.