When you consistently take action on the small things that excite you each day, you tend to get bigger, more significant things to act on, until your days become a synchronistic string of events that let you know you're on the right path.
Be honest with yourself about what sparks you and take action on it. Don't worry about finding your one true "passion." That's too abstract of a concept to figure out logically. Instead, start by acting on the small things that excite you each day.