I’ve had a phrase (originally from my AP English teacher way back when) that has helped me out whenever I got stuck while writing: “You can’t edit what you don’t have written down.” No matter how crappy the first draft may be, it is much better than having no draft. Remembering this has forced me to just write whenever I felt stuck. The editing process is better than sitting there in front of a blank piece of paper, waiting for perfection to emerge.
I want to make an analogy to life in general. Perhaps I could phrase it this way: “You can’t improve what you never try.” It is better to try something and fail than to sit there and wait for yourself to do it perfectly.