People always say to follow your passion, but what does that mean? To me, your passion is something that you're curious about to the point that nothing will get in the way of you learning more. Even when you can barely stay awake, you're still eagerly trying to absorb as much knowledge as possible. This kind of intrinsic motivation is hard to fake; you'll know it if you have it.
Motivation and passion aren't the same thing. Your passion is unlikely to change because it's what makes you tick.
When you have this kind of insatiable appetite for information, work and play start to blur because you can't focus on anything else, even if you want to. Instead of trying to find your passion, think about curiosities that never seem to go away regardless of how much you research them.