My first trip outside the United States was when I was 13. It wasn't just a trip, but a family relocation: Washington, DC to Houston (2-3 days after Hurricane Alicia roared through town...our hotel room carpet was wet from the windows to the beds) to Amsterdam (layover) to Dhahran, Saudi Arabia. Talk about culture shock.
How was it life changing? I'd never left the US before this, and I was a teenage. Within 2 years, I'd been to a dozen countries, lived on three continents and experienced things that the average American would never understand. To call it life-changing is an understatement. I wouldn't be the person I am today had my parents decided to relocate us.