What should I be when I grow up? How do you know?

I’ve pretty much worked in the same field since high school — I got a job pasting up newspaper pages using X-Acto knives and hot wax when I was 17 and I’ve earned my paycheck from something related to writing or media ever since.
This week I met a friend of a friend who is studying criminal justice after getting fed up with her previous career in fashion.
I found myself simultaneously impressed by her bravery to make a big leap, and overwhelmed at the prospect of how you’d do that.
It’s not that I’m only interested in one thing. Actually the opposite. If I were to ever make a career switch, part of what I’d find most daunting is how to narrow the myriad choices.

If only life's decisions involved just two choices. How do you pick when faced with myriad career possibilities?

I love to cook, but I know enough people in restaurants to know that’s a difficult path. But working for a farmers market or an upscale grocery store or a cookware store, who knows?
I love animals but it would break my heart to see them suffering at an animal shelter or vet’s office. But doggy day care or grooming or dog walking?
Is there something I don’t even know about yet that I could excel at and love?
This About.com article called How to Make a Career Choice When You Have No Idea What You Want to Do breaks down the process into some sort of obvious steps like taking self-assessment tests, making a list of possibilities, talking to people, narrowing the options.
When I was in business school, I spent what felt like an eternity taking an online self assessment career test. After answering hundreds of questions about my skills and interests, the wizardry of the test told me I’d be good at public relations. OK, so the test worked, because that’s the job I was already doing and I’d like to think I did it well, but I was kind of hoping that after getting an MBA from a top 10 business school, I might make a leap into something new and challenging.
Fortunately I lucked into a job where I’ve had the chance to develop new skills while bringing with me my earlier life experience in news. It’s sort of the best of both worlds to blend continuity and change.
For those of you who’ve made a big career leap, how did you decide to do it?
For anyone contemplating a change, what’s your process for making the decision about whether to do it?
Here are some online career assessment tests that are free:

For $75, you can take Career Leader, the test Michigan offers its MBA students to help in career selection.

I'm Colleen Newvine, and I would love to help you navigate your evolution or revolution
Let’s work together