In the Prlogue, how did the way that Adam felt about the war change?

At first Adam felt that the war was a front row seat to a great movie. Even during his second deployment, he loved it. When he was shot at in a firefight, it gave him a sexy feeling. Then his next deployment, it began to feel bad. When he would get in the Humvee and drive down the road, he could feel his heart beating. Then some of his men died, he was in several explosions, and he had a bullet skim across his thighs. He started waking up thinking that the war was hell.