Fill in the blank with an event or achievement that has happened to you or in the world in your lifetime that you never thought would ever happen.
This can be phrased as a good thing: I can't believe the USA elected a black president in my lifetime.
Or a bad thing: I can't believe I had a triple bypass operation in a sandwich shop kitchen.
I shall start with something small.
I can't believe I got a job that is as good as my father's was.