After all those years of automatic success, you don't get nervous any more. It's really necessary to be nervous and be a little bit frightened. It pumps the adrenalin into you and you really get down there and try.
The problem is, is when your focus is created by a crisis, then the frontal lobe shuts down essentially, the frontal cortex which is your intuitive intelligence. So you get very clever and very stupid in a crisis. Also, you pump adrenalin into your body from what you - physiologically you'll crash.
Research, for me, it's trying to get a mood, a mood of a place and style of people and it's also trying to boost my confidence and get the adrenalin flowing. I go off on my trips to odd places and dark corners, feeling somewhat apprehensive and nervous.
When you're working through the [fight] scenes, you're working on such adrenalin. And then, later, you're like, "Oh, god, my back hurts. Where did that come from?" Your entire arm can be bruised up, but you don't even think about it while you're working.