I VERY NEARLY joined the Army when in my early 20s. What stopped me were two things:

1. You sign a contract that says you will do the job for a period but that they don't guarantee that the job is available and they can put you in any job they want. I realized I could be peeling potatoes for years.
2. I couldn't believe what complete assholes the people in the recruiting center were. You want me to join you? How about being nice?

I ran the hell away from there having done everything except take an oath.