Ok, I already posted one mental self-manipulation technique today, here's another (epistemic status on this one is much worse): theoretically, and my experience seems to bear this out, if you do X thing halfway, then switch to thing Y while trying to retain (or, typically you don't have to try) the information pertaining to X in your head, then you've just successfully loaded both X and Y in your head simultaneously. For instance, you're writing something down, then have another idea and go to write that down, your brain has to remember what you were doing with the first thing, so you now have two things packed inside your mind

The utility to this, potentially, is that you can load up your brain with a bunch of concepts simultaneously by simply writing a description of a concept, stopping halfway, then going to the next one, and so on until the end, then finishing the last, and going back to the second to last, finishing it, and so on until the beginning

I haven't tried using this deliberately for this effect too much, I just usually notice it in passing when I stop what I am doing, for instance, to write a stupid mastodon post like this one...