For me, I decided at 745 am EST, on 9/11/2001, that I was joining the military. Problem I had was deciding which branch. I talked to all but the Coast Guard. Only one that would take me at 17 was the National Guard and they were offering me free college and a 2k bonus. I was leaning Navy and Active duty Air force, but the navy had retired its battleships, which is what I wanted to serve on, the Air Force couldn't/wouldn't let me pick what I wanted to do. The Marines the same way. So I went Guard. I don't regret the choice so much as I regret not switching branches after my first 6 years to Air Force or even going Air force to begin with. I think I would have enjoyed it better. The shooting and blowing stuff up fun I had originally in the Guard wore off quickly and it was no longer fun.