Permission to be wrong
If you give yourself permission to write a bad first draft, you almost always get a good second one. If you don’t, you get nothing — because there is no draft.
The blank page beats most writers because the blank page is winning a fight you haven’t agreed to have. You’re trying to write something good. The page is trying to make you stop. The way out is to stop trying to write something good. Write something bad on purpose. Then the page has nothing left to threaten you with.
You can’t edit a blank page. You can edit almost anything else.
This isn’t a productivity tip. It’s a posture. The writer who is willing to be wrong in a notebook nobody will read is the writer who eventually says something nobody else has said. The writer who refuses to be wrong is the writer who never finishes anything.
Be wrong on purpose for a while. See what happens.