Intense fear comes in waves; the body can't stand it for long at a time.
When I stand on the edge of a cliff or right at the edge of a building or something, it's one of the few things that gives me kind of a deep, overwhelming, irrational fear where it affects my physiology.
The last time I was this scared, I peed myself." "The last time I was this scared," Radar says, "I actually had to face a Dark Lord in order to make the world safe for wizards.
Something indefinite is always worse than something definite, a strong fear that doesn't last very long is easier than one that's nebulous but doesn't go away.
It's amazing how much of a bodily experience being scared is. It doesn't take very long of hyperventilating to feel like you're going to pass out. It's one of those things where being scared is more of a physiological response that you can pretty easily manipulate. So in those types of scenes, it just takes a lot of energy.
I turn into a crying, hysterical maniac when I see a spider. It's pathetic.
