You must have faith.
That's the conclusion I've come to after all these years of writing. The cornerstone of becoming a writer and continuing on in this odd field is faith. By that I don't mean religious faith, but a personal faith. You must believe in your story. Believe that, with enough work, the words will take the proper shape and become a perfect (or as perfect as possible) story. Believe that each word, each sentence, each paragraph is getting you closer to your goals. Believe that what you will create will be worth it in the end (that worth can be defined as making money or your actual happiness with your story).
This "literate" faith is what carried me through having my first six novels rejected by publishers. I certainly had my doubting moments (or even months) but after ten years of trying my first book was published. It was important to believe in what I was doing. I still need faith now--the act of beginning a novel is an act of absolute faith (perhaps even more so since I don't use outlines). The road does get rocky at times, either I can't solve a problem or a character goes off in a direction I don't expect, but I believe the answer will come. And so far it always has.
So have faith. The rest will fall into place after that.