Military is a great place for a jock. That's the first thing they test you, they test you physically. If you can run, if you can do the pushups, it's not as hard a transition. If you can't do that, you're going to have a problem because they're going to really work it out of you or work it into you.
You could be a Green Beret and a kid could jump out from behind a building and hit you with a rock. No matter how tough you become in the military, there's a way to die: there's nothing safe about it.
Being in the military just lets you know how helpless you are. You could train forever but you're still at the mercy of someone in the Pentagon, or somebody in the rear moving you around like a chess piece.
