Not always as straight forward as you may well know, this elusive feeling can be a bit tricky to get your head wrapped around. But, I've got a few thoughts around it I'd like to share that will hopefully clear the fog around the subject.
:: do something/anything ::
A lot of times we look for a passion without a starting place. Especially at a young age as there, often times, isn't as much life experience to draw from. Growing up in a small city with really only a handful of things to do, I spent a lot of time with friends and family and even more time playing computer games. Excitement for me was the next new and fascinating game that I could throw myself at for weeks or months. Often times I would get dad ire when he woke up at 6AM for work; me having not slept at all, still playing the game I was enthralled with when my dad went to bed with that all too common phrase "don't stay up too late". Having spent a great deal of time surrounded by things I was comfortable with and that gave me a feeling of entertainment it's not hard to draw a conclusive line to the outcome of moving out of my hometown to a place I'd never lived with no family or friends within 10 hours of me. Soon after the games I'd been playing and the TV shows I'd been watching failed to perpetually entertain a young adult with literally nothing else to do in a place where there was nothing else to do (at least in my mind): Total. Mental. Breakdown. Why am I so bored? Why does everyone have a passion except me? How does everyone know what they want to do? Why can't I find something I'm interested in? Eventually, after some tears were shed and some terrible things were said the depression let up enough and I started seeking help in the form of self-help books. "Maybe there's something useful in these", I thought to myself. It was at this point that I stumbled upon Imagine by Jonah Lehrer. This book was quite literally the turning point in my life. I'll never forget what this book taught me: No one knows what they are passionate about at first. They just try things, get really good at them, and then find out later that they are passionate about the things they are good at. People are often times driven by their own success with a thing. How do you know if you'll be successful at something? By trying it, failing, trying again, and probably failing again - until eventually you have a small win and that small win leads to bigger wins. "This is fun!", right? Passion is ignighted from curiousity and fueled by perseverance. Sit and ponder on that for a while; it's worth the investment in time.
You can't possibly know what you're passionate about without trying, failing, and eventually succeeding at any one thing. So, do something; anything. And do it often. Passion will follow.
:: find your pair ::
I've noticed at times that I'd suddenly feel extremely modivated after watching something, but could never put my finger on why that was - until recently. That spark of insight? Fairly obvious in retrospect: if you know something that drives you and can pair that with something you'd like to try, then look for someone who's been successful in pairing those two things and seek inspiration and motivation from their progress. So, if money drives you and writing a book is something you want to try then look for others who've successfully written a book and made money then study them and follow their future endeavors; it might just draw out a bit of motivation seeing something you want as achievable by someone not dissimilar from yourself. As an added bonus the thing that drives you may very well keep you going in those moments of struggle that come with trying new things.