In our teens, hormones are running a three-ring circus. In our 20s and 30s, we're consumed with what we'll be. In our 40s, we're consumed with what we are.
Then comes 50. The half century mark. If we believe we're all going to live to be 100, we're half way there. If not, we're on life's downhill slide.
It's a time for personal reflection. Where have I been? What have I done? Who am I? What do I do now?
Here is a random list of personal thoughts in the measure and meaning of a half century on the planet.
You're reading this list. Congratulations. Elvis didn't make it this far.
You start to check out celebrities who are turning 50. Even factoring in personal trainers and plastic surgery, there is good news for 2013 and 2014 on what 50 looks like: Johnny Depp, Brad Pitt, Lisa Kudrow, John Stamos, Conan O'Brien, Michelle Obama, Matt Dillon; Rob Lowe, Edie Falco and Elle MacPherson, Mike Myers,
You start to read more about the future of artificial body parts.
The older you get, the less you care what people think about you. As others do the same, there forms an unspoken agreement: we are what we are.
You start to realize that the things that attract you to people are the same ones that attracted you in grade school.
Gravity is going to win, but you and modern medicine are still strong enough to fight back.
In baby boomer time, you're one of the kids.
You're old enough to realize all the things you used to believe that aren't true, but young enough to still have a lot of years not to believe them.
You can hear people say: "Sixty is the new 40" and think you still have ten years before you hit middle age.
If 60 is the new 40, then 50 is the new 30, which makes you Gen-Y, which means you're living in your parents' basement.
It gets harder to hold a grudge because you kind of forget what made you mad in the first place.
You realize that doing nothing is not necessarily a waste of time.
It's a time of experience and possibility: Been there, done that. But haven't done all of it.
"Now or never" applies to more of the things you haven't done.
Your knees are a little stiff in the morning. But there is still time to run a marathon.
If you haven't grown up by 50, it's ok - there's not much you can do about it anyway.
Mick Jagger and Keith Richards are 20 years older than you, and they still have groupies.
You finally come to terms with being called sir and ma'am. In your forties, that could cost a waiter a tip.
You worry less about avoiding temptation. But temptations seem to be better at avoiding you.
You've come to terms with the things you don't like about yourself and, in fact, a couple of them have become kind of cool.
Time suddenly becomes a bigger part of your life, and you feel a new urge to fill it doing what you love.
You've learned enough hard lessons to realize that it's important to take life more seriously than you take yourself.
You understand what Carl Sandburg was talking about when he wrote: "Time is the coin of your life and only you can determine how it will be spent."
You might be muddled enough to forget where you are, but still confident enough to change where you want to go.
If you want to really appreciate how great it is to be 50, ask someone who is 70.
Don't worry too much about the ticking of the clock. In 20 years each click will sound like a rifle shot.
In your forties, you're afraid you're turning into your parents. By 50, you realize you were right.
You realize the professional football players look like they're 12.
You realize that all those years spent trying to find balance, you might as well been trying to lead into gold (which may ultimately turn out to be easier than balance.)
Disappointments can accumulate - as Lilly Tomlin said "Just when I think I'm too cynical, I realize I'm not cynical enough.
As a French proverb says: Forty is the old age of youth; 50 is the youth of old age.
You think back to when you were twenty, and how you thought about people who were 50.
You've accumulated the wisdom of half a century. Now if you could just find your keys.