From Randy Seaver's GeneaMusings (a bit belatedly). Here is your assignment if you choose to play along (cue the Mission Impossible music):
1) Did you or your ancestor make a critical life decision that really changed their life in terms of place, work, family, relationships, etc.?
I think all people make a multitude of critical life decisions over the course of their lives. Things like changing jobs, deciding on a college or career or to join the military, getting married, having children, and moving will alter the course of your life.
My ancestors that most changed their lives with one decision were those that decided to get on a boat and cross the Atlantic to come to the US from wherever they lived in Europe. Some of these people came with only pennies to their name, in search of a better life for themselves and their family.
In my own life, I would also equate critical decisions on moving, though on a smaller scale. I moved to Syracuse 10 years ago and everything changed because of that: I met my now-husband, decided to get my MSLIS, had Julian. All things that most likely would not have occurred in the same way had I stayed in Oneonta. I can't imagine my life any other way, so I think it was the right move.
If you're interested on a fiction book that shows how even minute changes effect your life, I highly recommend Dark Matter by Blake Crouch. It is one of the best books I've read this year and well worth the hype.