So, it's well-known (or, at least, oft-thought) that you can't just work 16 hours a day; if you want to get stuff done, you need to rest from time to time. You have to take breaks.
Today, just now, I realized that I don't really know what the best way to rest is. If I want to rest, should I do something that's fun and interesting, like reading a fantasy novel? Should I do something that's boring, like building roads in Minecraft, so that work will seem comparatively interesting when I get back? (And besides, reading a fantasy novel is a bit of a challenge, at least for me, whereas building roads in Minecraft is trivial.) Physical activity probably helps, but how much? Do relaxing activities, like taking a warm shower, help more than just sitting there? How can I tell when it's time to take a break? How can I tell when it's time to get back to work?
(Suggestions for tags would be appreciated.)
When in doubt, try a cheap experiment.
Make a list of various forms of recreation, then do one of them for some amount of time whenever you feel the need to take a break. Afterwards, note how well-rested you feel and how long you performed the activity. It shouldn't take many repetitions before you start to notice trends you can make use of.
Although to be honest, the only conclusive thing I've learned from trying that is that there's a large gap between "feeling rested" and "feeling ready to get back to work on something productive".