While I was in school me and a mate both used to save up to go to our nearest Delta Force site every 6 weeks or so, and I always loved it and so started searching online for what kit I could buy.
Anyway, I ended up buying myself a full setup a few months after I turned 17, saw somebody putting together a scratch team for Div 2 NSPL on their forums, asked if I could play, and that was that.
As it was div 2 and before that day I literally hadn't even shot my marker, had never set foot on a sup'air field, and had no idea what I was doing, I spent most of the day being shot out quickly, doing daft things, and occasionally somehow playing well, we won Div 2 that day, and I was absolutely hooked.