I learned today that some people think of "passion" as when you enjoy your work. I've never really meant it that way? When I say I'm "passionate" about something, I mean that thing is my Favored Enemy Type and I am prepared to kill it with a hecking knife.
Passion comes from a latin word meaning "suffering" [1]. An act of passion is one of pain, of madness, of spite. If you are a passionate writer, then you are pissed off at your book for the crime of not existing.
Inside you is a curious, creative spirit, which can look at the work to be done, and imagine that work as a looming monster, a giant beyond comprehension.
Also inside you is a violent little goblin that thirsts for giant blood.
That's what passion is.