I've seen a few videos of people discussing their ADHD. One thing that came across is "I can't focus" was too broad. Some of them could sit for hours on end mastering a video game. What they could not do is focus on things that were less interesting.

Mind you, these were high functioning individuals. They found ways to use their bountiful reserves of energy to earn a lot of money. Maybe there are others that can't focus on anything for a long period - I don't know.

The difference between them and myself (apart from that energy) was that I can, with a struggle, force myself to focus on most things if I'm physically comfortable. That said, doing something I don't like is struggle, and I'll procrastinate like crazy. But for them, it seemed near impossible.

They solved the problem in the same way I do for regular things I don't like doing. They incorporated it into their daily routine. Repeating a routine, even something a simple as casting a fishing line (which I guess is not that simple to do well, now I think about it), brings it's own pleasures regardless of the task. For me it takes a few weeks to add something to my routine. For them, it seemed to take months or years. The self discipline they applied to keep at it until it became a routine they enjoyed for it's own sake, was amazing.