Not sure if just trying more methods will help you, but here are some that happen to consistently work for me:
- Always work with a list.
- When everything seems overwhelming and I can't get myself to start, just pick ONE item from the list.
- If there is no list, just making the list will do. It may be empty. Done for now, enough, no need to start on it yet.
- Granular items.
- Instead of "pack suitcase", break it down like "get suitcase out".
- Split the task of "read X" and "understand X". That stops obstructive thoughts like "I wouldn't understand it anyway, and then I'd need to as ... but can't right now because ...".
- The only new breakthrough from this year: When even doing one item from the list feels like too much, only simulate doing them in your head: https://lemmy.ml/post/36147982
- I have a section of "structural improvements". Those are things that, once done, improve my life, forever. E. g. getting this diagnosis. Getting a dishwasher. Getting a maid. Unlike, for example, clean the kitchen, which is temporary.
- implementation intention: Might feel overwhelming to "stop browsing right now", but set a timer to stop in 5 minutes. Or "when the timer finishes, I'll do the simulations on list items".
Real habit building still does not work for me, though, even with a specialist therapist. That'd be the real deal.

I finally became more aware of this and realise mid-response that this is nonsense. But by then I'm invested.
My solution: A file "nobody-cares.txt" where I can paste it, which feels easier than just closing the tab.
Therapist says this is a fine first idea, but by doing so, I still attribute value to this nonsense. So next step is to just discard everything I had typed. Actually feels good sometimes.