My senior year of high school, I went to a party at CalArts, wandered through the animation department, and watched Pete Docter shoot his student film. I'd never seen rough animation before. That's all it took. I've always drawn. I've always loved animation. I had no idea how it was made, or that people actually got paid to do this stuff.
Twenty-five years, 100+ episodes of TV, half a dozen pilots, multiple shorts, and a feature film later, I still can't believe I get paid to do this stuff.