Missed purposes

I spent the better part of last night wondering if maybe I somehow missed my calling. Which isn't to say that I have any clue what I should have been doing with my life by now. There is just this nagging little suspicion that I made a wrong turn somewhere, and the job I was put on this planet to do, got lost along the way.
The thing of it is, if I had made a different turn at most key points, I never would have found my wife. Granted, I would never have know that, but now that I do, I couldn't think of any other path.
Is it possible to go back and figure out where you were meant to wind up? We all say that we would do things differently, knowing what we know now. The problem with that idea is that time only flows one direction. Even if it could reverse, the physics would prevent you from ever remembering how things turned out the first time around. The scars in our brain tissue that form our memories would be wiped away as everything else reversed.
That might be a little bit hard to picture.
Think of it like this, our days are like words and pictures drawn on a blackboard in a school. We start (at least in the English language) on the left side of the board, and write to the opposite side. If we were to reverse time, letters would be lifted from the board and the chalk redeposited on the stick.
Whoa, that was deep.
What I have been trying, in my usual round-about way to say, is that there was a job that I was supposed to do when I was born, some way that my life was supposed to affect something. While there is no proof of it, that work feels incomplete to me, somehow. It would be so much easier if our lives came with instruction manuals.
Then again, most guys would never read theirs anyway.