You want to be brave but gunfire gets you running. Hemingway's definition of courage rings in your ears as you run like hell. Fight or flight. Grace under pressure. It should be a mantra that one can rely on but if you read The Short Happy Life of Francis McComber or Red Badge of Courage then you know it does not always come the first time. In both of these stories the hero is found wanting in the first engagement with a lion or war. The fear is something you can taste and grace deserts you in that first flash.
You tell yourself that the next time you will look and see what is going on. That you wont succumb to the numbing rush of adrenaline that gets you running like a star halfback. It is a very powerful drug. That you will somehow fight back and get control of yourself. In the Hemingway's short story and Red Badge of Courage both protagonists assert themselves in the second brush with death. One dies in the process and one makes it through but they have conquered their fear and grace is present under pressure.
The problem is you don't know when that second challenge will come. It may never come and you want to think that you will be ready. But it is the very randomness of a shooting that is terrifying. You don't know. Nobody does. All you can do his hope that is doesn't and if it does you will be able to grab a little grace under pressure during the primal fight to stay alive.