At what age do you officially become old? It's a question that many of us ponder ... and fear.

It's also a question that the American Association of Retired Persons (AARP) recently posed to a handful of millennials. Their answers — and their vision of what it means and looks like to be "old" — makes for some rather hilarious, if not painful to watch, video. Take a look:

To put it kindly, the millennials in this video are fairly brutal in their assessment of aging. But hey, we've all been there, haven't we? I can vividly remember when my parents turned 40 and thinking that they were positively ancient.

Ah, to be young and to think that youth is the property of a specific age. Now that I'm in my 40s, I can vouch for the fact that 40 is nowhere near old. In fact, after reading about folks like the 103-year-old British marathoner Fauja Singh, I really can't think of an age that I do consider "old."

Hesitantly, I posed this question to my daughters who are 10 and 13. They bounced the idea around a bit before settling on 70 as the age when a person becomes old. I was pleased that I had a long way to go before hitting this milestone. But then I reminded them of their grandmother — who is almost 70 — who regularly hikes and walks with us when she visits. She plays — and often wins — rounds of kickball with them in the backyard. And she always crawls around on the floor with them during their games. And there's their great-grandmother who was chastised by several family members last fall for moving tables and other heavy objects in preparation for her 90th birthday party.

They smiled at all of that and shook their heads in agreement, before my eldest summed up her thoughts eloquently:

"You could be in your 30s but if you don't do much you could feel old and people might see you as old. But if you keep on being happy and living you may never really get 'old' no matter what your age is."

My teen will be glad to hear that this theory has actually been proven by a recent study that found that not only does good health make us happy, but happiness makes us healthier.

I can live with that.