So many people choose to quit. Choose to stop living. They're really cheating themselves, you know. I think people don't really understand what they can accomplish if they want to. They have no idea how talented they are.
I think you find another side of yourself when you actually put your heart into something. That's one of the things that makes marathoning special... it's one of the few times when you actually meet the challenge of doing something that is probably the most physically and mentally difficult thing you've ever done.
For me, I can't recall anything more difficult than finishing a marathon. Maybe that's why I've done so many of them. It's one of the few times in my life when I've felt completely self-fulfilled.