You want feelings of mortality? Find yourself working for someone who was in kindergarten when you entered the ranks of the employed.
Gulp. Yeah, that'd do it.
As a matter of fact, I hired (about 6 years ago) a young man who has done very well in his job, and has recently been promoted. So, kudos to both of us.
Just recently (like, Friday) I retired (YAY!). The week before I retired, the young man and I were discussing his father's health problems. His father is 5 years younger than I am...
You could die, you know. Then they'd quit asking those things. They wouldn't quit sending you the mail, though - we still get mail for my father-in-law who died in 1984.
On the whole, though, I suggest that you just remind yourself firmly: old age and treachery will always win out over youth and skill.