This. It also depends on why you're resting. If it's just part of a long term training arc something like swimming, yoga, or slow extended-reach shadow boxing drills will keep you loose without overtaxing you. I take occasional ballet classes to sweat while giving my body a break from regular training and remind myself I'm a girl. It's good to get your head as well as your body into a different space.
If you're resting because you're worn out or broken, stretching and sleeping is helpful.