I have big wall dreams this summer, and want my cardio to be solid after cleaning/jugging pitch after pitch.
I setup a a pulley system in a tree in my backyard. With one person feeding rope out through a GriGri, the other can jug ~50m of overhanging rope...continuously!
Give me a holler if you'd like to come over and get some cardio in! I like to do this in the evenings, after getting on real rocks :D