One of the biggest, and possibly the biggest, obstacle to becoming a writer... is learning to live with the fact that the wonderful story in your head is infinitely better, truer, more moving, more fascinating, more perceptive, than anything you're going to manage to get down on paper. (And if you ever think otherwise, then you've turned into an arrogant self-satisfied prat, and should look for another job or another avocation or another weekend activity.) So you have to learn to live with the fact that you're never going to write well enough. Of course that's what keeps you trying -- trying as hard as you can -- which is a good thing.