I have worked with several writers whose primary challenge was taking the step of sitting down at their desk. Their anticipatory anxiety or other resistances create a mental barrier against taking the first step. Often they are entertaining an inaccurate and exaggerated estimate of the agony that will ensue if they write.
I love to swim but I dislike getting into the water due to the brief shock of the initial chilliness. I spend a good bit of time on the deck pacing and postponing my entry, but once I dive in and do a couple of laps, I’m plenty warm and I enjoy being immersed. Diving into the water might be momentarily uncomfortable, but it’s not anywhere near as agonizing as my mind makes it out to be.
Writers who have difficulty starting often do fine once they have taken the plunge. The challenge is to set up your writing life to increase the odds of diving in.
Make your writing a daily habit, like brushing your teeth, so you don’t have to think about whether you will do it or not. And remind your pacing, skittish, shivering, self that the chill will be over quickly, and that the water is filled with treasures.