Heights have always made me "nervous", in that my mouth would go dry and my palms would sweat and, at times, I would uncontrollably tremble. It didn't stop me from repelling down rock faces in Yosemite, or joining the ladder company in the local volunteer fire dep't. Madness? Death Wish? Maybe just a thrillseeker.
Mental picture for acrophobics: you climb, alone, 50 maybe 75 feet up an aerial ladder to put water on a burning house. You're spraying 500 gallons a minute with such force that every slight movement causes the ladder to groan and twist in the opposite direction. As you move the stream from one window to another, the water column hits the building between and you're violently flung backward until it reaches the next window and you drop immediately towards the fire. Your pants still dry?