You will never accomplish something big, it is too daunting Your mind will trick you out of starting.
Instead, start small. Pick up a pen and jot/scribble/doodle for 2 minutes.
This will loosen up the open self who wants to create. By feeding this creative self, and getting addicted to the good feeling. You will gradually build up to an accomplishment, note by 2-minute note, until the mass self-organizes.
Subsequently, bigger things are less daunting: they simply come out of lots of small things.