Don't set goals. Set constraints.
Do you ever set goals just to find that you cannot meet them?
I’ve done that too. I know it works, but only short term.
Embrace constraints
Creating artificial constraints empowers creativity. To spark creativity artists are known for limiting their tools to, say, one color, musicians to 5 notes, writers to 50 words (Dr. Seuss) etc.
Instead of saying I am going to write 500 pages today (goal), say that you are going to write for a short period of time (say 5 minutes).
You might not have to create constraints. Recognize constraints that already exist, and embrace them.
It might be a technical limitation, a deadline, limited scope. Pick one, just one feature. Design for just one persona.
Possibilities are there. Find them and embrace them.