It’s a matter of will, turning off the paranoia, thinking rationally, and knowing that you’re safe here. An amateur would lie awake all night, starting at every noise, making up sounds when there aren’t any. He’s hunted enough guys to know that their own heads can be their worst enemies. They start seeing things that aren’t there, then, worse, not seeing things that are. They worry and worry, and chew on their own insides, until, when you do track them down, they’re almost grateful. By this time, they’ve been killed so many times in their minds that the real thing is a relief.