if you have have the knees for it knock yourself out. Unfortunately I was hit while riding motorcycle by car so running is out for me :/

Trail running/hiking probably one of the best exercises you do. Just want twisting your ankles and knees from roots and things.

I find I get more joy out riding a bike. I think nothing of a 5+ hour ride with friends on a weekend. If I am hiking 5 hours I want a view to make it worth it. ha-ha