If your chasing cardio there is bound to be a pump track near you in GA. Google the term pump track to see what I'm describing. I have one on my property and ride it 2 or 3 times a week. I also have several dirt jump lines ranging from 2' to 7' tall with gaps 8' to 15'. I'm way too old for this kinda stuff but really enjoy it and so far no serious injuries other than a blown disc in my neck.