Interesting question. For me, resting was similar to exercising an antagonist muscle. Or oversimplifying it, do the opposite of what you were doing. So if your day is full of focus and concentration and sedentary then do something physical that doesn't require a lot of focus and concentration. Doing something physical all day? Then relax your body by reading a book on the couch.

You'll probably need to experiment to see what works for you and come up with your own answer.