Mixture. Never liked red meat in the first place and by the time I was 18 I probably already had a 95%+ vegetarian diet. Still consumed products that aren't vegetarian, like certain sweets, snacks and beers, still had leather shoes and belts.
It wasn't until about 26 years old that I took on all the trappings of vegetarianism properly. I don't tell people I am vegetarian until the last minute if necessary. I once told a girl 3 dates in and my best friend from school has no idea, despite all the times we went to McDonald's and I only bought fries he hasn't put 2 and 2 together