When I start a story I am not worried about the word count because I am usually sucked into the story and letting the words flow. But usually about the middle of things I start to wonder whether I will have enough words to make a full novel. It feels like I could wrap up the whole story in only ten thousand words. Is there enough story to fill in the word count? Do I have to add more threads in to make it?
Except the story has already made that decision. If I continue to let the words flow, they will come out to a word count close to what I want. I try to remind myself of the matter every time my mind brings it up to worry over, but it will always come up at some point in writing the story. The best solution is to lose myself in the story so that nothing else matters until it is done. It is hard but so is blocking out any editing voice from my head.