^That's funny, my first answer was going to be "walking around in the woods".
Besides that: riding bikes, playing guitar, playing video games (too much of that, honestly), archery (recurve). I used to be really into rock climbing but the friend I did that with moved and I was never into bouldering. Before the archery, I had a brief but deep flirtation with shooting sports but it was expensive and you would meet a lot of people who ,uh, were perfectly nice to me but would express some really shitty views about others.