Failure, losing, setback.  Whatever word you want to use to describe the situation in which you don't achieve your desired outcome does not matter, what does matter is your mindset when this occurs.  Do you hate losing... even more than you want to win.  Do you use the outcome of failure to evaluate what went wrong in your preparations or execution in search of lessons learned.  Do you use the setback to fuel your practice and preparations even more.  The mindset of excellence is to use failure as input into the next round of improvements and trials and to fuel the motivation to train and prepare even harder.  Greatness knows that achievement never occurs without adversity, is never realized without struggle and is never pain free.  But the mindset of the greats is to use these failures and setbacks to become even better and not to run away and never try again.  Success occurs because of the adversity not in the absence of it.  Embrace the challenge, the difficulty and the failure, it is what creates the excellence inside of you.

Failure isn't fatal, but failure to change might be. John Wooden

If you're not prepared to be wrong, you'll never come up with anything original. Ken Robinson

Failures are finger posts on the road to achievement. C.S. Lewis

Every adversity, every failure, every heartache carries with it the seed of an equal or greater benefit. Napoleon Hill

Failure is so important. We speak about success all the time. It is the ability to resist failure or use failure that often leads to greater success.J.K. Rowling