Personally, I like to tinker with stuff - nothing that requires a ton of concentration, but just taking stuff apart and putting it back together.
If I have an audiobook, listening to that while doing a repetitive task is really relaxing as well. Things like knitting or crochet seem really good for this - I don’t do either of those but I have other little crafting type things that I do.
I also like to re-watch old startrek episodes while scrolling lemmy but that feels less relaxing.
I used to do videogames a lot and that was fun but also less relaxing then the other things.