I'm afraid I can't relate. I initially invested a lot of time in my first choice of career (over a decade) and just left last year. I walked out the door, said goodbye, and the next day it was out of my mind. That being said, I think the key is keeping a strong mental separation between "passion for a field of work" and "predetermined path by society to actualize that passion". The latter, in my opinion, is something that one should never get attached to.