So said my brother, currently training to be an illustrator. Beginning a piece of work - in his case a painting - knowing that it's not going to turn out as you hope it will. Is it better to begin knowing that it won't be as good as you hope - but know that it's another step on the path; or to begin believing that what you make will be perfect this time - and then face inevitable disappointment?
This is where deliberate practice comes in. You choose to begin, knowing that the work will stretch you, knowing that you're likely to fail, but also knowing that the work will make you a little bit better.