Afraid of heights is a poor way to put it.

Take you and I for example. We're in the ring about to square off. You know for fact you're going to taste canvas. You're scared. It's your first time. The 2nd time around, same thing, you're scared. You eat canvas again. However, as time goes on and you step in the ring, time after time eating canvas, you eventually get use to the taste of canvas and yet, you're fear level for the event is waning.

Going up in trees is like that. The more you do it, the more you get use to it.

iSnipe