I know of my fear of heights since childhood - was bad at picking apples because I required a rock-solid fit of ladder into three, rather braved parental displeasure than venturing higher than perhaps 6 m (20 ft), absolutely did not lean out to pick that elusive apple. Came down from ladder visibly shaken.
As an adult I feel queasy walking the edge of the Swabian Jura escarpment and I am noticeably more circumspect than my fellow hikers on trails with a sharp drop on one side. You come to a scenic clifftop with me and you notice that I keep well of the edge.
Well I foolishly agreed to a nice afternoon at a local high rope course three photo galleries of other users walking the courses. Then wanted to back out but did not.
When we were introduced to the harness and belay system this reassured me a bit. Climbing harness plus one rope with a normal carabiner and one with a carabiner and rollers, i.e. you were always secured with at least one rope if you followed proper procedure (I had two hair-raising moments later on the course when I observed my companion doing clip off, clip off, clip on, clip on instead clip off, clip on, clip off, clip on).
We walked the three easiest courses for adults, for two and a half hours, and at first my knees were trembling every time I reached a platform but it got better with time, and the first time I slid down a steel wire to ground hanging in my harness I got to totally trust the harness. It’s a curious feeling - one moment you think you are going to jump off a 6 metres height, and the next moment you are hanging in the harness and just slide on rollers along the inclined wire feeling totally safe.
It was just lack of proper balancing technique that wore me down in the end - I tended to hang from my arms on the safety wire rather than walking on my feet with my hands on the ropes of the course. On one of the last elements I had to give up to exhaustion of my upper body strength trying to put my feet into loops hanging down, and just hang in my harness and pulled myself on a guide rope to the next platform, feeling embarassed but safe.
I am so going to do that again some time.