Heights never bothered me which is good thing considering all the rock climbing I used to do. Only one time I got kinda freaked out. I was doing a big climb in the Sierras and was about 1,000 feet up. I was belaying my partner but there was no ledge or anything to stand on so I was just hanging there, trusting my weight to these little metal things wedged into a crack in the rock. The wind started to pick up and began to literally blow me around. I suddenly became aware of the fact that I was really, really fucking high up in the air. Sometimes when this happens to a climber you can just bury your head into a crack so it doesn't feel so bad. But this rock was really smooth and kind of convex, like being on the outside of a round glass, so you could see all around you. Like it or not. My heart started beating really fast and I almost started hyperventilating. Fortunately my climbing partner caught up to me and was able to get me to focus back on the climb ahead. Weird, never happened before and never happened again but it sucked when it did.