The first serious thing I wrote was my fanfiction: Breaking the Mold. I was between jobs and needed to fill in the time until my contract started with the job I am currently having. I remember it was my Vampire the Masquerade phase, I was crazy about that game. Not only that, but I read all the books I could get my hands on.
So, I decided to write a fanfiction. I started. I cracked up 5k chapters, something I now know not to do, in a single day. Sometimes even two of them. It was easy, considering I used the Hetalia characters as templates and the lore from the game.
Then, I rushed the ending, my job started, and I didn't start writing again until after the busiest campaign at work ended, which was August last year, I believe.
The second time, I started writing because I was bored. The first, to do something about my excitement, which drove me crazy with all the bottled up energy.