Most people would advise you to, calmly, break the task at hand into small tasks/steps. Personally, my problem is that the tasks are too high level (maybe an epic), which makes them overwhelming. By breaking them into easy-to-do-steps that forces you to plan your solution (1st point) and understand the problem (2nd point). You should break them into SMART goals (you've probably heart about this concept already). By having a list of really really small items you get a feeling of progress every time you tick an item off the list; that progress should keep you going! Starting is the hardest part, there's some inertia to it; so make the item so small you'll have no excuse not to do it. Remember: if you still feel confused about an item/urged to procrastinate you probably didn't break it down enough.
The sensation of ticking off items is what should get you going; that's what gives you the sensation of progress and that enables the feedback loop. Physically ticking off the item (pen and paper) is even better. So actually write your list (on paper or digitally using Trello, Todoist, etc.), don't just "think it"; that's key.
Meditation is also good to sharpen your focus.
P.S.: I'm also a procrastinator; there are good days and there are bad days; there's no cure. This is the kind of thing that is managed.