There is a paradox inherent in any creative act. It's only when you accept this paradoxn that you will feel comfortable and create with greater ease. The two parts:
1. More often than not, we fail to achieve our creative vision. Seldom does the thing we want to create turn out to be as good as we hope.
2. Each time we create, we have to assume success or at least the strong likelihood of success, because without that we will not have the energy to persist.
Another way of saying this is that we have to learn to accept "good enough" while never stopping striving for perfection.
Well, if it was easy, everybody would do it...
(for help being more productive, see my book, "Focus: use the power of targeted thinking to get more done," published by Pearson and available from Amazon and other online and bricks and mortar book sellers.)