You should really change your definition of slow...8:00 miles are nothing to scoff at right off the couch. I'm training for a multiday running event in January (if you've never heard of Disney's Dopey Challenge I suggest you look it up) and I USED to run sub 35 min 5 mile races when I was in high school in central MA (if you know where Holy Name is located you have an idea of what our XC course looked like), so hills included. I'm lucky to go sub 10 min over any considerable distance now. I'd love to see what I can crank out in a flat out mile, but injury risk is too high. Slow it down a bit, get the legs into a little bit better shape, then start pushing the pace. Don't forget, you don't want to be training at a pace that leaves you completely exhausted after 3 miles because you'll still have 10-15 miles on the bike and another 3 mile run after that.