Who currently living on this planet hasn't heard the statement that you are only as old as you feel?  I know: deaf people.  The rest of us have heard it over and over and over and over again until we wish we were deaf, too.

All of us actually have several ages.  The first age is our chronological age.  If you were born on January 1, 1960, then on January 1, 2005, you turned 45 -- no ifs, ands, or buts.  You have about as much leeway fiddling with your chronological age as you do making time run backwards.   You can lie to other people about your chronological age or get a facelift to conceal it, but that doesn't change anything.  Your body is still that age.   

The second age is our biological age.  Basically, how well do we measure up in terms of fitness, weight, and mental acuity against an average cross section of people of similar chronological age?   There are various tests you can find on the internet that purport to assess your biological age, your real age as they describe it, by asking a series of questions.   For more accurate results, you could visit a medical office which could check your body for arterial plaques, bone density, body pH, skin laxity, and breathing capacity.  These tests are meant to measure how fast your body is aging.

All of us chronologically age at the same rates.  Any person born on January 1, 1960 is 45 years old on January 1, 2005.  But we don't biologically age identically.   If you were to meet two men, both born on January 1, 1960, one could look significantly older than the other. 

When someone asks us to guess his or her age, they mean their chronological age.  How we assess that age, on the other hand, comes down to what I call someone's physical age, the third type.  If we saw a twenty-year old with gray hair, we'd age him as older; a sixty-year old with brown hair and few wrinkles, as younger.  A person's physical age is usually related to his biological age, but not always.  A thirty-year old man may be in fantastic physical shape and have a biological age of twenty-three, but if he's completely bald, we'll still guess him to be thirty-five. 

In effect, what we do when we guess someone's age is compare him or her to the mental snapshot we have of various people of that or similar ages.  When I was a grade school student of six, I could pick out the nine year olds from the seven year olds.  This is because I had a clear mental snapshot of how most kids my own age looked and could judge others as being a few years older or younger by how much they differed from my mental composite.  Today, with childhood far behind me, I cannot easily discern a child's age since I don't spend the majority of my time with that age group.  I no longer have a firm mental image of how most six-year olds look.   A kid could be six or he could be eight.  I can't tell.  I can just venture a range of ages the kid might be.   By the same token, young children have no categorized mental images of how most twenty or thirty or forty year olds look.    They lump adults into very few age categories.   An adult is either their parents' ages or their grandparents' ages.   A kid might be able to say that a young adult is younger than his father, but he won't be able to guess by how much.

When we are children, it is flattering to be thought of as older.   We feel more mature, more adult-like.  What seventeen-year old doesn't want to be mistaken for twenty-two and allowed to buy alcohol without being asked for ID?  But once we reach adulthood and can legally do anything our parents can, the thrill is over.  Now, there's no concrete benefits to being older.  By thirty, we're hoping we will be asked for ID.    

For this reason, whenever a woman asks me to guess her age, I always say "twenty-one."  It's the least offensive answer.  Girls both younger and older than twenty-one will be flattered by the reply.   If it's evident the woman is far older than twenty-one, it's still wise to just say twenty-one anyway in order to keep the conversation lighthearted, which it most certainly won't be if you are forced to commit to an age.  I've found that if you guess a woman to be thirty when she's twenty-eight, a close enough guess in my opinion, the woman will still be grossly offended. 

Most people are not objective about their physical ages.  No matter how ragged they really look, they tend to think that people view them as younger than their chronological ages.  It's easy to hear only what you want to hear and con yourself that at age forty, the masses perceive you as no older than twenty-five.  You'll know at forty if you really look twenty-five because enough people will treat you like a person shortly out of university.

What I'm trying to establish is that everyone has some physical age that most people perceive them to be.  For the majority of us, I'd guess that perceived physical age to be � 3 years one's chronological age.  The average twenty-five year old will be pegged, by most qualified guessers, to be between twenty-two and twenty-eight.  A qualified guesser in this case would be someone who comes into contact with enough twentysomethings to be able to make a decent guess, someone probably between the ages of eighteen and forty.  If we were trying to ascertain the age of someone who was seventy-five, qualified guessers would be people over the age of sixty.

If we can't be all that objective about our own physical and biological ages, how can we be objective about how we feel?   Let's say you're thirty-five years old right now.  Can you actually remember how you physically felt when you were twenty-five?   Unless you're in bad health now and were in good health then, you're not going to notice the difference.  Those who do lots of physical activity -- stuntmen, athletes, manual laborers -- are more cognizant of declines in physical performance.   An Olympic class runner or swimmer will observe his speeds decline and find it increasingly more difficult to compete against younger competitors.  The damage to joints takes its toll, the recovery time between competitions grows.     Such people truly feel the differences ten years bring.   The rest of us are clueless. 

When a seventy year old woman announces that she feels young, what does that really mean?  That she feels sixty-seven?  That she feels fifty?   How can one know he feels young if he can't easily summon up muscle memories of the way he felt at twenty, at thirty, at forty?   I'd say "young" only has any meaning here in an abstract sense.   The seventy year old woman feels young in that she's still open to activities typically thought to cater to younger individuals. 

In reality, I don't think it's as simple as people being as old as they feel.  Rather, I think they feel as old as they're perceived.  When I was in college, there was a guy named Richard who lived in my dormitory suite.  Richard was only a year older than I, so at the time he would've been twenty.   However, Richard wore a hat and dressed in shirts and slacks from a different generation.  He walked to classes, not with a knapsack like everyone else, but with an old-fashioned briefcase.   He looked more like he was thirty-five.  I told him this once and he wasn't insulted at all.  He'd often heard he looked like he was in mid-thirties and seemed glad by it! 

Richard looked thirty-five and acted thirty-five, and so by most people who were none the wiser, he was treated as if he were thirty-five.  In Richard's situation, he made a conscious decision to jack up his physical age.  Most of us don't do this.  We just go about our daily lives and other people perceive us to be a certain physical age, which we pray is a decade younger than our chronological age, but which can be five to ten years greater than it if we're really unlucky. 

If you're a thirty year old who physically looks forty-five, I don't care how often you repeat the mantra that you feel young.  People will treat you like a forty-five year old.   If you're single, you will attract potential partners who are typically attracted to forty-five year olds.  If you look forty-five, enough people will treat you like you're forty-five , and eventually, you will feel like you're forty-five.  By the adage "you're only as old as you feel", you're now forty-five.

No thirty year old would readily admit he feels forty-five.  How could he?  No thirty year old has ever been forty-five yet to know exactly how being forty-five feels.  But if the thirty year old paused for a moment, he'd realize he didn't yet have to be forty-five chronologically to know what being forty-five felt like.  Feeling forty-five isn't completely the physical part of having a forty-five year old's pulse rate and forty-five years of wear and tear on the body.  Feeling forty-five is more like the way a person feels when s/he's considered forty-five by virtually everyone s/he meets.  

There's actually a fourth type of age.  I didn't mention it before because it's not something that can be objectively measured, whereas there are agreed-upon indicators that govern chronological, biological, and physical ages.  This last type is mental age.   Like biological and physical aging, mental aging occurs at variable rates.  There's no doubt that one's mental age is affected by the rate at which one biologically and physically ages, but it's not completely dependent upon it, and for some, not dependent upon it at all.

Mental age is why most forty year olds no longer wish to hang out at college fraternity parties.   They're on a different wavelength than the typical twenty-year old.   They've been out in the working world, possibly been married and divorced and had kids.  Even if a person never physically or biologically aged after the age of twenty, he would still continue to mentally age.   His outlook on life normally changes with the passing of the years, and this is reflected in who he chooses to keep company with, the topics which occupy his mind, and the activities he decides to pursue.   By no means does this hold true across the board.  There are forty year olds who physically look forty but who have the mental ages of a twenty year old.  They continue to exhibit the same behaviors and dwell on the same problems they did when they were chronologically twenty years of age.  We all know or have heard of people like this.

I'd argue that it's this last type of age that has the greatest impact on how old you 'are.'   If you have the mental age of a twenty year old, regardless of how you may look, you only have the capability to deal with life as a twenty year old.  It does you a disservice to look older than twenty because others will treat you initially according to your physical age, although you're not able to see life like someone of that chronological age would.   For a dramatic example of this point, think of a ten year old girl who looks sixteen.  She has a mental age near ten, but young men who see her will approach her and speak to her as if she's sixteen.   It's not a very healthy situation for a ten year old to be in.