I understand your fear I have a little myself. I occasionally have to climb up on stuff at work I’m not comfortable with. The only way I’ve found is just force yourself to do it it sucks for a while but eventually it gets easier the more you do it.
I can force myself to a degree but that anxiety leading up to making myself do it sucks I know rationally 10-15 ft isn’t anything to really worry about yet when the time comes I can’t do it without going through every possible bad scenario