Last season there was a gentleman who had to walk the entire way - he was plagued with knee pain and if I remember correctly it took him over 13 hours. The important thing was that he kept going and he finished.
I've been pretty down on myself lately for my "slowness" and last night's episode couldn't have come at a better time. I may not run a marathon in 4 or 5 hours, but I am going to do it and I AM going to cross that finish line! And once I do, no one can take that away from me.