Back in 1995-6 I was in Secondary School (roughly high school for you US folks), and a friend of mine got me in WH40K. This was 2nd Ed, when it wasn't all so remorselessly po-faced, and still had a sense of humour. I got into the background a fair bit, and I'd always been one for writing my own stories, creating characters, and so on. 
My friends and I did this for our own amusement - not 40K characters, but superheroes and the like.
Anyhow, I checked out a local game store, tucked away in a dingy, all-but-forgotten mall in my town on a whim after being into 40K a fair while, but finding it lacking... something, and thinking more about the character side of things, and making up our own adventures.
I found out about the gloriousness that is Role-playing games, and bought Mekton Zeta, a mecha-based RP system, as it tickled the bit of my brain that is permanently devoted to Macross and Gundam.

I tried to understand it, and to run it with a few friends. But as the old saying goes, Roleplaying the first time is a bit like sex for the first time. You don't really know what you're doing, and it feels a bit wrong and secretive, but you know you're having fun, and that it feels pretty good. And the more times you do it, the better it gets. 
And this was pretty much true - we ended up getting into a bunch of other games, and my friends got into role-playing as much as I did, and we purchased many gamebooks and systems, and played the hell out of them. 

Eventually, people moved away, and our lives all changed. We still played tabletop together where we could, but I wasn't getting the game I wanted from my local group, so I wondered about gaming online, and looked into it. I first found out about Yahoo Groups, back when they weren't the crapfest they are now, and got into a lot of hit-and-miss games on there around 1998-2000, and then didn't really dabble in online much other than a handful of things here and there. 
Around 2003-4 I got the impetus to set up a game on Yahoo called 'Thunderbolt Black', about a group of Mercenary fighter pilots. Shock, awe, surprise, it was a hit, and it's still lurching along (barely) now. 
From that, I got into a few more games. I joined an awesome Ace Combat one called 'Chasing the Sunrise', which then died after the players all decided they liked WoW more than the game, and I drifted about a bit, before finding the Guild off of TV Tropes around four years ago. I lurked for a while, and then finally decided to take the plunge and make my own game, which has been churning along after numerous re-boots ever since. 

So, I've been roleplaying in one form or another for about eighteen years. 

(good grief, I feel so old)