What an interesting question. Well... I've been in love with books as far back as I can remember. At 14, I decided to dabble in writing, myself. I was horrifically amateur, but it was fun, and I steadily improved as I kept reading and writing.
I'd have to ask my husband what year it was. He remembers it better than I do, because it was what really brought us together. (What a twist, I know; the guy remembers a date better than the gal does? He's a keeper, I tell you.) But I clearly remember that it was writing with him that made me realize 'well, damn, we really do have a shot at this'.
We were running a forum-based roleplay together, something vaguely based on things like Final Fantasy, and whatever else we felt like throwing into the pot. We had other participants, but they were sporadic at best. The two of us, though, spun a huge, dramatic story between us, and one of the other 'writers' said that we really should try getting something of ours published. We pushed our story onward, revising the borrowed ideas out and replacing them with original material. We kept writing this story in installments over the next five years.
Now we're married with three complete trilogies and then some between us. If only I can revise one to a point that I'm happy with so I can take the plunge into our first submission...