Focusing is hard. There's too much to be done, even limiting to things that I care to do. Focusing means (?) picking just one or two of those to do, and not doing the rest. Unkindly, that is: Leaving the rest to rot. That is difficult.
Maybe a better way to think about it is "pick one brick." (Quote of the quote.) You're going to get to the other bricks in due course. But you're going to start with the upper left one.