Started out by renting the 1986 movie from a local video store when I was like ... four or five? This would've been '94 or '95.
Blew my mind. From there I rented every other G1 tape they had, which was a decent smattering of Sunbow season 1 episodes.
Beast Wars hit shelves very shortly after that, and, although I actually didn't realize they were related to Transformers yet, I thought they looked cool and had my parents buy one. (Razorbeast)
Then the cartoon hit the air, I quickly realized it was a sequel to Transformers, which was awesome, and I watched it through to the end with my friends each week, explaining any of the references I could.
I built up a pretty sizable collection of Beast Wars figures, which are still sitting in a tub in my parents' garage, and actually got my hands on some old G1 toys as well, which were always kind of mysterious to me and a huge treat.
I don't remember when or how I got back into it again as a late teen/early adult, but like most things from my childhood, I found I still got a huge kick out of it, and I've been eating up the fiction (though not the toys) since.