I think it's less about finding your passion and more about aligning your natural God given talents to your line of work. For example, my passion is golf, but there is no way I'll be able to make money playing golf. I certainly don't want to be a golf pro or manage a golf course because that means I'm working in golf rather than playing golf.
My God given talents is I'm a people person like my dad. I love to talk to new people, learn about them, their life, their kids, their problems. I truly love to talk to people and learn from them as well as teach them. So, knowing that, there were a ton of careers I could go into, Financial Planning, Teaching, many kinds of Sales/Relationship/Account Mgmt jobs, etc... I love numbers, math and finance and it comes natural to me to run through numbers in my head, so I landing on Financial Planning/Business Consulting and I love it, plus I get to golf a lot!
Although I love numbers, I could never do a job where I stare at spreadsheets all day or sit behind a computer all day as I need interaction with people, face-to-face. I have friends who hate to talk to people and they love staring at spreadsheets. I have a friend who is a CPA and does taxes for people all day everyday which I would hate but she loves it as it combines her love of Accounting with people interaction.
Also, there are some pretty cool personality tests which pop up if you Google them. I've taken many tests to help me identify my strenghts and weaknesses and that really helped me identify what makes me happy doing and what makes me miserable.