I think perhaps that some people are passionate people and will be passionate about whatever they do. And others aren't and won't.
To me, if you simply do what you like to do and not what you don't like to do, you can't help but be passionate about things.
I know that's pretty simplistic, and sometimes you have to do stuff you don't like, but you'd be surprised at how much of that you can "get out of" if you're smart enough!
