I don't think I've had any periods longer than a year or two when I didn't ride, but I think when I realized it would be a life long interest was in the early 80's when I was stationed in Germany with the Air Force. I didn't have a car while there, and explored the region with my bicycle, a $100 Huffy Concours from the Base Exchange.
Had a blast, and knew I'd stick with it. When I returned stateside, one of the first things I did was to go buy a better bike, an '84 Trek 520.