Lots can be said about this movie. I considered posting the entire drill scene, but this fragment captures it pretty well on its own. Buy this movie!

In the military, you are confronted with your drill instructor practically immediately, he personifies violence and aggression.
Brutalization and desensitization are what happens at boot camp. From the moment you step off the bus you are physically and verbally abused: countless push-ups, endless hours at attention or running with heavy loads, while carefully trained professionals take turns screaming at you. Your head is shaved, you are herded together naked and dressed alike, losing all individuality. This brutalization is designed to break down your existing mores and norms and to accept a new set of values that embrace destruction, violence, and death as a way of life. In the end, you are desensitized to violence and accept it as a normal and essential survival skill in your brutal new world.
-- On Killing: The Psychological Cost of Learning to Kill in War and Society, Dave Grossman