In my night class, I insist that, although the male students might want to report their true ages, we females (instructor included) are all 29 or younger. I must confess that I look pretty damn bad for 29, and each time I mention something like: "I've been teaching since I was about four years old, since I'm only 29 now," my class explodes with laughter -- despite my threats to fail them all when they do so.
The day before my most recent 29th birthday, I was attending a meeting with three colleagues, one of whom wished me a happy 49th. Another woman said, "I didn't know you were 49! I thought you were younger."
"I'm 39," I told her, after giving her a big hug. "I just look old for my age."
Some friends offered to "have my birthday," and I was eager to comply. "You can have it," I told them. "I certainly don't need another one! In fact, you can have all of them."
Of course, the alternative to having birthdays is not all that appealing, especially as I feel just about as good, as fit, and even more confident than I did when I was 29 for the first time.