Build something your fear cannot argue with because it already exists.

Fear is excellent at arguing about the future and useless against the past. It can produce endless reasons why the thing will not work, and none of them apply to something that has already been made. Existence settles the debate in a way that no amount of reassurance can. That is why finishing even a small, flawed version of the thing changes the internal conversation so much.

Take whatever you have been planning and produce a rough, complete version of it this week. Not the good one. The existing one. After that, the argument is about improvement rather than about whether you can.