But does one's calendar age "really" describe or define them? Talk with some people in their 50's, 60's, and 70's+ and see if they don't tell you that they feel about the same at their stated age as they did 20 or 30 years earlier. Sure, they can look at old photos in a picture frame and then in the dressing mirror and see the advance of time. Yet not see or feel about life much different today than they did in those earlier photos.
This is the point at which calendar age becomes much more abstract than the number that represents it.
As an aside, I'd point to a movie with Jack Lemmon titled "Save the Tiger". Lemon delivers a line, "we live in a country that worships youth like it's some kind of a God". (or something like that) But when you think about how marketing shapes our perceptions, it targets people in their primary acquisition years until they become empty nesters. Around 45 or so. People after this age have generally accumulated everything they need and aren't so represented as being young people any more. After that they may become active in volunteer organizations or social groups and feel about the same as ever.