I'm sure you've all heard the old adage: failure is not an option.
How would you ever learn from your mistakes if you don't fail at something? Having the mindset of "failure is not an option" will make your life stagnant, where you'll be afraid to try new things, explore new frontiers, create a better life for yourself, your family, and mankind. Writers (and everyone else, for that matter) are bound to fail, so fail in style and learn from those lessons of failure.
But what does failing really look like? Failing, to you, may be receiving a rejection letter from an agent or not having anyone show up at your book signing. Do we quit at that point? No. Pick yourself up and persevere. In my opinion, a rejection letter is not failure. It's part of a writer's life. Quitting, mind you, should never be an option, depending on what quitting looks like. Smoking or drinking yourself into oblivion or abusing drugs (or any other harmful activities) are the exception to the no quitting rule.
So, my friend, continue to strive for excellence.