Honestly, the first thing I want to say is:
When can I go again!?
That was the most fun I've ever had away from home. It was a blast, and I learned a whole ton about myself and what it takes to keep going.
When you feel like you can't go on at all anymore, when you feel like you're going to collapse and fall and lay there, I can say this: keep going. Focus on moving your feet one at a time, and do not let yourself fall. Focus on an objective.
"Just to that tree... now to that rock..."
Do not give up. I was so close to being done with a trail, and I was one of the one's in the lead, and I tripped on a rock. I was so tired, I didn't want to get up. But I did. I got up and rounded the bend and saw the end of the trail. Without that rock there, I would have seen the end and probably would have run the rest of the way. But the rock was there, and I didn't see. If I had given up, then they would have found me sitting on a rock, only about 4 feet away from a cliff face that lead to a river at the bottom.
I got up. I finished it. And when you feel like giving up, press harder; because usually the end is closer than you would think.
Okay, so I'm officially not scared of heights. After facing a 165 foot sheer cliff armed only with a rope and a 'beaner, I'm feeling pretty good about myself. I repelled down it and many more while down in Moab, and I've found my real fear.
Going downhill on a bike. Scares the crap out of me.
Anyway, have a good day!