"When once a decision is reached and execution is the order of the day, dismiss absolutely all responsibility and care about the outcome. Unclamp, in a word, your intellectual and practical machinery, and let it run free; then the service it will do you is twice as good." -- William James
In other words, when you've decided to go for it, just go for it. Don't second-guess yourself and don't worry about your results from moment to moment. Your'e in it for the long haul.
Some long hauls are longer than others. My "Writer's Block" screenplay took 13 years to get made (as "The Real Howard Spitz") Another one, "At Sea," got ripped off and still hasn't been produced (at least not my version); when it is made it'll overshadow that 13-year wait.