I struggle w this too. No good links to share but IME it's primarily emotional not logical. It helps if you can find some spark of enthusiasm for a specific tiny single step, because having started makes it possible to get into flowstate and/or discover other potential hooks or (re)entry points for the next time.

If genuinely "stuck", try stepping away from it, going for a walk, and considering the simplest thing that could possibly work; ok to start there and refactor later.

Making plans? Think big. Making progress? Think small.

Also, standard self-care stuff (sleep, exercise, meditation) is critical.