Just write it down
I’ve lifted weights for sixteen years. The hardest part of the entire routine is putting on my gym clothes. If I can muster the energy to change, a cascading sequence is set into motion that almost always ends up with exercise.
Writing is the same. The hardest part is starting. You just need to put a few words on the page and that same cascade is unleashed. You create a spider web of expanding possibilities with every additional word, drawing closer to something cogent and worthwhile at an ever-increasing rate.
Every hesitant word, ugly paraphrase, and unfinished thought creates optionality for your future self, putting more pieces on the table for you to play with.
So just… Write it down. Capture everything. Silence the self-doubt and start, in whatever capacity you are able. It only gets easier from there.