Age: Is it really just a number?

My birthday is coming up soon -- the 23rd for curious readers -- and I keep thinking of the scene from "When Harry Met Sally" in which Sally cries about turning 40. Harry asks when and she replies, "In six years, but I'm still going to be 40." My 40th is not yet here, but I keep thinking about the number. Forty is not that far off and it sounds so grown up. But I don't feel grown up. And if I believe the masses, I look much younger than my age. So if I don't feel or look grown up, and if 40 is the new 30, why am I worrying about aging? The issue permeates every aspect of my day:

• While brushing my teeth in the morning, I study the wrinkles over the bridge of my nose. They are only visible when I squint, but the lines are deep. I look at the grooves around my mouth and I wonder how long they've been there. I question the elasticity of my skin. I'm even more obsessed since a dear friend, who has a flawless complexion, told me about a recent encounter in which someone told her she looks older than her oldest sister.

• I've always admired my mother's silver hair (I've only seen her with naturally dark hair in old photos), but I'm freaking out about the ones on my own head. I'm thrilled they are silver and not a dull gray, and I don't want to dye them because I don't think I could keep up with the maintenance. Yet, they are everywhere now and they won't behave, so I curse them. A cool streak might be okay, but my hairs stick out at all angles and drive me nuts.

• Every morning I also see on the scale the pounds I've gained since arriving in Kuwait. I've modified my diet -- all except for giving up chocolate -- yet they stay. I know more exercise would help, but ... And I wonder if it's all futile as I hear my sister's words echoing in my head that I'm old and the weight gain is unavoidable.

And while I try to come to terms with aging -- I'm cool with the concept, but the reality is a bitch -- I have to ponder the effects of age on my relationship that is or isn't. I've come to terms with the fact that my friend, although grayer, is younger (it's only 1 year and 11 months, but I'm used to dating men 20 years my senior). Yet I can't help but think that at my age, every day, month, and year is magnified and matters. I still haven't decided whether I want children at all, let alone naturally, but at my steadily advancing age, the decision may no longer be mine. If he follows the example set by movie and music stars, he's got at least 40 more years to decide if parenthood is for him. I don't have that luxury. I'm beginning to think it's now or never as I was rudely reminded this week in an editorial by English doctors that women can't have it all. You can't beat biology. Still, I don't want to do something stupid because 20 years from now I might have regrets.

So am I simply obsessing about another thing I can't control or are my concerns valid?