I think mine, as mentioned in another thread in here, was through spending years creating my own worlds for roleplaying. I spent a seriously large proportion of my time doing this, or actually playing the games. At the same time I was burying my head in every fantasy book I could find. I'm sure what I write now must be seriously influenced by this background.
In a way, I actually feel strange being labelled as a writer though. In my eyes I'm actually a scientist, and I was always taught (by someone who was very blinkered) that the two did not mix (maybe it just means that I'm a very poor scientist). It does give me two very separate lives, however.
For example, the infamous incident where I got so completely hammered that I woke up the next morning in a hospital. only to discover that I'd fallen off a cliff the night before
It's off topic, but Plastic's post remided me of an incident that occurred when I was a student. Myself and a friend were taking a shortcut home from a hectic nightout through the grounds of a local hospital when we decided to have a look around inside.
Anyway, we went in through this service door and were wondering about through some deserted corridors when we heard some people coming towards us. In panic, I ran away the way I had come from while my mate jumped out of an open window. To cut a long story short, I found him a little later on his hands and knees crawling away with a pair of sprained ankles. It turned out that though we hadn't gone up any stairs, we'd actually gone up several wheelchair ramps and were no longer on the ground floor when he'd made his leap for freedom.
Worse, because he daren't go back to the hospital in case they recognised him, he dragged himself around for over a week before he realised he wasn't going to get better on his own.