You can categorize passion under two things only and those are,
LOVE & HATE.
If someone thinks clearly, then whatever work we do or we've done or we'll do in the future are based on how much love we have for that work.
The basic idea of being successful in any field of life is to love what you're doing.Until and unless there's a purpose in your life you're dead.
So spending a good amount of time in figuring what you love is equally important as compared to working hard.