If this interests you try reading "The Quiet Soldier" by Adam Ballinger. Its a great book that details the selection from start to finish. The author had no previous millitary experience and at 26 years old joined even though he had a nice job, fiancee, and a degree. This was in the late 80's (1989 I think.) Anyway its a good read if that sort interests you, or if you like millitary things in general.