Birthdays ending in 0 are monumental. They are a time to reflect on life; to reconcile what has been accomplished with what has not, to re-evaluate expectations and contemplate a life that may one day include Bocce Ball. Or worse, endless golf.

That is, of course, unless you turn ten.

In which case the only reflection you remotely understand is the one in the mirror and the only significant accomplishments to reconcile are the number of permanent teeth in your head. Heck, when you are ten you don't even understand what words like "reflection" or "Bocce Ball" mean.

My wife and I have boy-girl twins who recently turned The Big One-Oh. We celebrated their milestone birthday as a family with something they love: brunch at their favorite restaurant followed by insane amounts of coconut cream pie. We let them create a short list of their most desirous presents and then made sure they received every one. Except for the pony and the Lego Beach House in the Bahamas.

I remember my milestone birthdays. Most were accompanied by hangovers. My wife even threw a surprise 40th party for me when I turned 39. It worked; I was pretty surprised. And at each decade I took stock of my advancing years and gazed into the mirror of hope and expectations and dreams and accomplishments. I recommend not doing this with a hangover.

But my tenth birthday is somewhat murky.

At the time, I wanted to be an astronaut. My parents decorated my room with wallpaper planets and moons and stars and I hung model rocket ships from the ceiling and dreamed of traveling in space. I constructed a tight Apollo space capsule out of a cardboard box with elaborate gauges drawn in magic marker. I entered the final countdown sequence wearing long underwear and a football helmet. My co-pilot was a sock monkey.

I think on my tenth birthday I went to the moon and back. Or maybe it was the day after. Or maybe when I turned 21. Or perhaps, the night I turned 39. It's hard to recall exactly.

But I do remember this: when I was ten I could be whoever I wanted to be and do what ever I put my mind to do. The sky was not the limit, the universe was. All I needed was a cardboard box and a little imagination.

Ultimately I did not become an astronaut. But by the time I realized I would never fly in space, I had outgrown both my long underwear and my desire to sit in a tiny capsule with a sock monkey. I had no regrets; I came up with some new dreams—only to see some of those drift away in my teens. In hindsight they were pretty silly. Who would ever hire a kid to play a doctor on TV?

Several milestones later, I still feel that I can do anything I set my mind to do. It's just that, for practical reasons, there are things I no longer feel like doing. Playing Professional Football for one. And there are some things I am not capable of doing. Like singing. And there are other things that no one in their right mind would ever let me do. Male modeling for instance. But that doesn't mean I can't still be an astronaut one day.

We live in a rapidly changing world, a world I couldn't even imagine when I was ten. If I could, I might have converted my cardboard box into a flat panel TV and a Wii game controller. And before my Big-Oh birthdays are through, who knows, it may be entirely possible to fly into space with long underwear and a sock monkey.

I am not ready to give up on the possibilities, even if the possibilities become less appealing as I grow older.

But in the mean time, despite what I achieve or don't achieve, I know that I can be happy watching my children turn ten and twenty and thirty and forty and beyond. This seems doable. This feels like a pretty worthwhile accomplishment. Because I know that the important milestones in my life are no longer calibrated in decades, but by the on-going achievements of my children.

And the best present I can give them is encouragement. To let them dream. To help them do whatever they set their mind to do; whether it is racing a horse in the Kentucky Derby or building a second home in the Bahamas entirely out of Legos.

Hey guys! Remember the coconut cream pie? Remember how we shared the last piece until there was nothing but a crumb left and no one wanted to eat it because then your birthday would be over?

They probably won't remember their tenth birthday, but I will.