I didn't, and I wish I had. Back in the late 70s when I was of age, joining the military was a very unpopular thing for middle-class white kids to do - and quite often the ones who enlisted did so because they were ordered to by a judge. It was a different time.
But in hindsight I see I really needed to learn the things the military had to teach: discipline, teamwork, toughness, motivation and patriotism. And unlike today, I never would've come within 1000 miles of actual combat.
So I always try to give respect to the soldiers and vets I meet, unless they're complete assholes.
edit: To answer the poll, if I was 20 years younger I'd enlist, absolutely. If I was 15 years younger I'd give it very serious thought.