Just make it edible
Start with what’s possible, you'll probably exceed it
If you don't have the courage to be rubbish, you'll never start.”
I lived for a short time in a co-op in Berkeley, California where everyone had assigned chores. The first time I was assigned meal duty, I was nervous. I had never cooked for a dozen people, and I was desperate to cook something impressive. One of my housemates, Naomi, offered this escape hatch from my anxiety:
“The only requirement for dinner is to make it edible.”
In ideation, you should always consider the impossible, but when you’re you're having trouble taking action, start with what’s possible. Figure out the basic requirements and aim for that. You’ll probably exceed them.
So long as you do something, anything at all, you’re on your way.