The trick is finding something that you as a unique individual are both WELL-SUITED FOR and sparks some degree of passion for excellence within you. We've focused a lot on the latter, but far too little as of late on the former, quite frankly.
I've never been able to figure out that one myself.
I'm generally good at ending up doing things for which I am neither well-suited nor have any passion for.
The problem is that you have to pick *something* and then you are locked in, even though the only reason that you picked anything is because you had to choose *something*.