Everything good proceeds from enthusiasm. The sense of “I really want to know how this turns out” will drive you on through many, many long nights of no results, whereas the feeling of “I think I ought to do this” dries up very quickly.
The big mistake is to wait for inspiration. It won’t come looking for you. It’s not so much creating something, I think, it’s noticing when something is starting to happen — noticing it and then building on it and saying, “Okay, that’s new, that hasn’t happened before. What does it mean? Where can I go with it?”