Happy 50th. I was trying to think of something humorous to say about the advantages of turning 50 . . . but there are none.

Nope, none. Sorry.
But there is humor . . . my wife was at a chain drug store checkout & the woman asked for my wife's senior's card. Well, my wife isn't to the Senior's Card age yet & as with many 50 somethings, her aging can be a sensitive issue. Not necessarily her age, just aging in general.
So anyway . . . my wife went off with both barrels. "How dare you insult me" etc etc. And then she demanded the senior's discount. The clerk's 'No' was the wrong answer. More vehemence & a line forming. Then, the manager was summoned & he got an earful.
By the time my wife left, she had the discount & the manager was stuffing free goods in her bag as an apology.
Now, a young person wouldn't get away with that . . .
Ian