I think the earliest memory of this affecting me was on a family holiday at Girraween National Park when I was thirteen. One of the hikes called 'The Pyramid' saw me frozen to the side of, what's best described as, a large rock. I recall being left there as the rest of my family climbed to the top and then collected me on the way back down. I did manage to conquer it a few days later but still I was pretty darn petrified.
Another time, and this is a hang my head in shame moment, is the Giant Drop at Dreamworld on the Gold Coast. Basically, you get winched up a tower to 120 meters (or 39 stories) and then left to drop at roughly 135km/hr with your legs just dangling in free air. Once I was back on solid ground I cried. There, I admit it. I was 23 or 24 at the time and I cried like a baby.
Still, I haven't let these incidents deter me. So when my brother and I decided to do one of the alpine tracks at Lake O'Hara in Yoho National Park, I thought 'Sure, no sweat. How hard can it be?' Well, let's just say it wasn't a walk in the park. There were some parts that were pretty much straight up. It wasn't that that worried me. It was the straight down cliff that I was walking along that managed to freak me out. That and the melting snow on the track and the fact that I wasn't wearing hiking boots or I didn't have any hiking poles. My mountain goat of a brother just wandered up (and down) like he was walking on a footpath while I clung to the side of the mountain and managed one small step after another. There were times when I felt like I was going to cry and had little panic attacks every time my foot slipped but somehow I managed.
Once we got to the top the view was AMAZING! I'll let the photos speak for themselves though they don't compare with being there yourself.
Still, after all is said and done, I don't think I'd hesitate at doing something like this again. The reward far outweighs the effort and I feel that the more I challenge myself, the better I'll become at dealing with this little fear of mine - here's hoping anyway.