The first thing that comes to mind is phobias. I have a definite phobia of heights, but I’ve done various things over the years to challenge my fear and confirm to myself that I can still act (instead of just react) in the face of my phobia. I doubt I will ever overcome my fear of heights (in the sense of feeling comfortable), but I refuse to let it control me. So, I’ve ridden an aerial tram, I’ve walked across a pedestrian bridge very high above a freeway, I’ve climbed trees and tourist towers, I’ve done a few zip lines, and I even went bungee-jumping once.
So if I was going to add pressure in a training scenario, it would be to train somewhere higher up than I’m comfortable being (which, honestly, is anything above what I could jump down from without serious injury — maybe 5 meters?).