[walking]

Anything where I have to really focus on motor skills seems to work for me.

I used do indoor and outdoor rock climbing. I also used to free climb buildings, when I was younger and less risk-averse (I'm not suggesting anyone free climbs buildings; it's dangerous and illegal :P).

Right now I don't have the opportunities to do as much climbing as I'd like, and I started learning to play the violin. It has a similar effect because I have to really focus on what I'm doing, and there's no mental space for other issues. I'm also not really good enough for creating music to be a creative process. Mostly I just work on drills and scales. Doesn't really get you outside though.

Personally, if I really want to unwind my brain, I find a super pulpy book series and read it. The less intellectual the better.