Last weekend I ran the Richmond Suntrust Marathon. I was standing back with the 3:40 pace team when the marathon started.
I stayed with the 3:40 pace team running an 8:30 mile for 13 miles...
Then I hit the wall...

I was still able to walk, then jog, then walk, then run until I finished the 26.2 miles with a time of 4 hours 36 minutes or a (10:35 per mile pace).