ADHD meds and therapy. I tried a ton of different methods, but ultimately I was procrastinating for two reasons. 1) my brain finds the things I need to do under stimulating, which feels like pulling teeth, so it looks for stimulation elsewhere and draws me to a different task. ADHD meds give my brain the proper amount of stimulation/reward for doing things that need to be done. 2) for a variety of reasons, I had an underlying current of anxiety around the possibility of failure. Much easier to avoid failure if you avoid ever doing the task. Therapy helps me reason through the anxiety, and realize that I am essentially already failing by not trying, so trying involves a risk of success rather than a risk of failure.

Edit: I still procrastinate plenty, but significantly less than I used to. It no longer reaches a point of nearly ruining my life, now it is just an average level of procrastination compared to my peers. Instead of avoiding tasks for weeks, months, or years on end, I avoid them for a few hours, maybe days at most (if I have the luxury).