As long as I can remember I've been very competitive, I've loved speed and agility, and loved the outdoors. I did gymnastics, aggressive roller blading, and all sorts of outdoor games and sports with the neighbor kids. I kind of wonder why it took me years after getting a road bike for commuting to figure out I wanted to race.
And FF, I think your more likely to want more of it once you win. Hell, even 2nds and 4ths make me want more of it.