Bouldering.

About a week ago, my friend and I were up at Cascade Park, in Elyria, climbing around on some rocks when this guy comes out of nowhere making an impossible climb look like a staircase; so, we befriended him. Since then, we've climbed with him a couple times, and he's shown us different ways up rocks that we'd never even considered using. It's an awesome work-out, too. Days later, and I'm still sore.

From left to right: Steven Novel, Chris Fallon (me), Justin Sekarajasingham, and Sherpa.