Hardly even anecdotal, just my personal experience:
I always disliked sports, and I would't <i>dream</i> of entering a 'fitness center' or whatever they're called. I do a minute or two with hand-weights every morning, I walk my dog, and I bike [pedals, not motor] a bit - the oldfashioned way, nothing fancy or spandexed about it. But am often puzzled by everyone's physical passivity: I don't really get the point of escalators, for example. I tend to trot up the stairs if they are available, in the process generally overtaking the stand-still folks on the conveyor. It seems to work: I'm sixty and in very decent shape and excellent health.<p>As for kickstarting my brain when it goes mushy, honestly I find driving at least as efficient as walking or biking. Change of scenery, not <i>having</i> to think, seems to do the trick for me.