I looked up the word "Passion" on dictionary.com Here's the definition it gives:
Passion: any powerful or emotional feeling; strong amorous feeling or desire
I must say I was very disappointed by this definition. I mean, sometimes I have a strong desire for chocolate, but it's not my passion. (At least I don't think it is) The synonyms they gave were a much better fit: fervor, zeal, ardor.
Even still, I don't have an answer. I loved what one of my girlfriends said. "It's changing all the time." Now that I can relate to.
What is your passion?