The trick is to pick a combinations that works:
* listening to a language lesson when cycling (learning+sport)
* repeating flash cards in a bus, instead of doomscrolling (commute+learning)
* listening to a language lesson when cycling to work (learning+sport+commute - whoa!)
* thinking about my programming project when cleaning my home (work+brainless menial work)
In most cases this involves something that doesn't require to much too much conscious attention and something that does.
Multitasking two coding problems at once completely doesn't work for me but what you described works and I do that all the time.
There seems to be a language disconnect for the type of multitasking that works vs. doesn't work.
Probably easier to focus if distraction has moved to the old lizard brain.
I can't find an obviously good source to share, but there's plenty of research to check out.
> "The growing trend, especially among young people, to multi-task may seem wonderful. But actually, multi-tasking is most likely to interfere with focused attention and, in turn, degrade memory formation, recall, and thinking quality."
Eventually I realized that parallelization is not really possible, you end up making a mess of everything, and trying to be a rapid context-switcher - similar to the illusion of simultaneous multitasking on a single CPU core - just takes too much energy and time - 15-30 min to unload, clear the slate and reload with something else seems common.
Practically, this is why people working on difficult problems that require their full attention get really irritated by interruptions, and often prefer to work in isolation or only with like-minded individuals.+