These things don't occupy your mind too much until you pass 50, or for sure 60 for most of you. I say all this from a lofty perch in the midst of my 80s. That's when it gets serious. Friends and family begin dying off much too quickly for comfort. Children you once knew or haven't seen in a while are now voting adults if not parents as well. Then one day you realize you are *thinking* about it all the time - well, a lot of the time.
I've always liked the way Robert Herrick brought it together:
Gather ye rosebuds while ye may,
Old time is still a-flying;
Tomorrow will be dying.
A version of this was posted in January 2015. It just felt right today.