Try a good fuk and just for something a little different try it with a woman.
I do bicycle riding, jumping rope, or go crazy on a heavy punching bag. Mountain hiking is pretty good too if you want to make a trip out of it.
To be honest, the way I bumped up my cardio was taken shorter breaks between sets, while going heavier and heavier. You can try this. However, it might not replace an actual cardio workout (treadmill, stairclimber, bike, etc).
who was the 2nd gunman on the grassy knoll?