I too feel like this inbetween gym days even though I do other exercise as well. I was told feeling like this is also a symtom of Caregiver Burnout, but I'd say my mind is fitter than my body & its becoming imparient.
At the moment I go to the gym 3 times a week, Mon, Wed & Friday. On my rest days, I either go out for a short bike ride or walk my dog or even both. Sundays I also do some weight training with dumb-bells.