Building a new habit of discarding the first thing that comes to mind is very hard. I used to just write down whatever decided to manifest itself at the spur of the moment. I could write 3-5K words a day like that, easy. Now I know it’s not always the best thing. In fact, most of the time it’s not. Now I train myself to decide what MUST come, what will serve the story best, and so I discard and discard and discard before I find the right thing. Sometimes it takes hours, but it’s worth it.
That’s how my writing process looks now: mostly thinking and writing down very little .