In this case, from Carl Reiner to Justice Kennedy, in The New York Times:
I would like to start with congratulatory wishes on your forthcoming 81st birthday.
As someone who has almost a decade and a half on you, I can tell you this: It may well be that the best part of your career has just begun. As a nonagenarian who has just completed the most prolific, productive five years of my life, I feel it incumbent upon me to urge a hearty octogenarian such as yourself not to put your feet up on the ottoman just yet. You have important and fulfilling work ahead of you.
I am still aiming at making it to the year 2100.