When my in-laws were here, my FIL spoke a few times of his service in the military. He was stationed in this area for a few years and would make comments about how it had or hadn't changed.
Red was pretty enthralled with the whole thing. He asked me "How old do you have to be to join the military?" I wanted to tell him 50... because the whole idea of my baby going to war at any point in time scares the crud out of me. I would be proud of him, yet terrified. But, ya know, that whole honesty thing kicked in and I responded with the truth, "18" - which, even as I type it, knowing my 9 year old is HALF WAY to 18, it sounds SO YOUNG.
Red replied, "When I turn 18 I'm going to join the Air Force. And when I'm done in the Air Force I'm going to join the Ground Force." Makes sense to me...