There's a writing exercise called "burn the internal editor" which asks you to just write without lifting your pen for 15 minutes. It punishes you a little for stopping, reviewing, judging. Also, the end result is invariably "bad". The constraints basically force it. And that can feel nice, since it's not your fault.
replied to:What motivates you to do it so badly? Can you find ways to explore that while only gently experiencing the self-judgemental bits?