There seems to be this common misconception that if you float-along, for long enough, eventually you will stumble face-first into something that will fully capture your interest... and become your passion. However, speaking purely autobiographically, I have found this to not really be the case.
I think a basis for this idea of "spontaneous passion finding" comes from the mindset that people have genetic dispositions to be good at certain things. This logic goes something like: "Each of us has a specific activity or calling that we are meant to do and, once found, we will naturally excel at it". However, when we look at the success stories of the greats, this idea quickly crumbles.
A beautiful book that addresses the absurdity of this idea is Talent is Overrated. In this book author Geoffrey Colvin uses Bill Gates as an example, explaining that he obviously was not born with the computer "gene", rather, he found himself in a unique situation that offered him a various set of unique opportunities (growing up down the street from one of the first public computer labs--for example), and he took advantage.
I personally subscribe to this "make-lemonade-with-your-lemons" train of thought, and more specifically, the fact that Bill Gates--had his hand been dealt differently--could have just as easily became passionate and successful in the world of medicine (or rock climbing).
Now this understanding of how passion, interests, and success manifests itself in humans is simultaneously motivating and daunting. On the positive side, it means that just like we have been told since we were little kids, we really can do anything if we put our minds to it! On the other hand, it also crumbles the easiest cop out available, by making it erroneous to blame our lack of "natural" skill on our lack of success in a specific field.
The fact of the matter is:
Were all dealt different hands, and we can use our unique combination of circumstances to create something beautiful for ourselves. Just remember, in the game of life, none is dealt a royal flush. The people around you who may seem like they have the game beat, well, they put in work. And if you want to make something of your hand, you gotta do the same
Once you realize that, the age old, "Yeah, but he's a natural" excuse begins to look really silly.