@keikobadthebad already gave a good answer, but I'd like to expand upon it a bit.
> Sounds like the work might not lead somewhere you really judge is useful, or judge will be painful.
As someone with ADHD I have realized that my executive function goes to zero if I think doing something isn't worthwhile. Not if I consciously think it's worthwhile, but if I know deep down that it's pretty much pointless. Thankfully my brain is a pretty good judge of what is worthwhile. The value of doing something doesn't have to be intrinsic, it can be extrinsic. Right now I am thinking about a potential architectures I could implement at work, even though I'd like to enjoy the weekend. But it's easy to hyperfixate on because it delivers immediate value and gives me a consistent hit of dopamine. Before this job I was unemployed for 6 months, and became unproductive after 3 months and just started wasting the days. I was concerned that I would come back into this job and be unproductive. Nothing could be further from the truth. My brain just quickly learned that there was no carrot at the end of the stick (no impact of my software) as long as I was unemployed.
All that to say, it sounds like whatever you have been doing has been fruitless, or at least appears this way to the man in charge of your brain. Either you haven't been hitting consistent milestones, or the payoff isn't really rewarding.
A practice that has helped me determine which tasks are going to be easy for me to do is to think about how measurable a success metric is. If the success metric is just "learn a new skill" then I probably wont do it. If the success metric is to make something that will make my life or the lives of others easier, or something really kick-ass, then it becomes really easy to do.
You probably should sit down and think about what constitutes "success" or "completion" for each of these projects and think about why you think you want to do them in the first place.