About a week ago I was looking at my knee and saw a brown fleck of cereal. I wasn’t looking at my knee with purpose, but with that googly-eyed blankness that gets you into trouble when you realize your eyes have been focused for 10 minutes on a large frowning man across from you on the bus.

I realized the fleck of cereal had clung to me for hours—since breakfast. What a tenacious little flake! I almost admired it.

I leaned in closer to see how, Newtonianally speaking, the flake had held on, and then had a horrifying realization: That brown spot was no flake of Special K Vanilla Almond. It was an age spot.

I don’t like to curse in print, but my first thought was, “Are you fucking kidding me? An age spot?”

I’m 38, and apparently my liver is already preparing to jump ship.

The age spot is just the latest in series of sickening revelations.

Not long ago I went to the dentist because it felt like I’d lost a tooth. “See this big hole?” I asked my dentist, working my pinkie into the gaping maw that had once been a tooth. “I lufost a toofth, I finkf.”

“Nah,” he said, rolling backward on his weird little dentist stool, “you didn’t lose a tooth. They’re just crowding toward the front. It’s part of the aging process.”

I wanted to stand up, rip off the stupid bib and spit a plastic cup’s worth of Scope in his face. Aging? I had braces and glasses at the same time for nothing? My straight teeth—achieved after so much medieval torture—were temporary?

It’s just too much.

In the last couple years I’ve gone from not aging at all to being like an adult with progeria—aging 10 years for every one that passes. This suddenness of hips, of flaps where there once were triceps, has been so traumatic that every time I see a twentysomething woman on the street I want to grab her and shake till her belly button ring pops out. I want to send out a message in a bottle—so urgent, it’s basically a Molotov cocktail:

If you’re in your 20s, the total package of who you are will never be better than it is right now. Sure, maybe you’ll get a cute yoga butt when you’re 40, but you’ll have crow’s feet or veiny hands or an age spot above your right knee.

You think you know where your nipples are, girlfriends? You know nothing.

I wish someone had said all this to me even before I was in my 20s. In high school and college I wore billowing shirts and baggy vintage dresses to hide what I called my “pot belly.” I dieted and dieted. I kept a notebook listing every morsel that passed my lips. I went to Weight Watchers, then binged on ab-exercise books that gathered dust on my shelves.

Many times I had sex with the lights off because I thought my little belly would horrify the young men I slept with. They were probably just grateful, as boys that age are (another thing to remember, ladies).

A whole decade of my life was marred by time spent mooning over why my body wasn’t right. I hungered for answers, following every tidbit of advice burped up by Oprah and Geraldo. I spent hundreds of dollars: sports equipment, Cosmo by the cartful, diet pills that cost $30 a bottle.

At no point was I satisfied with my body. At no point did I look in the mirror and say, “I’m a beautiful girl.” But I should have. I should’ve known I was beautiful and young, and how ephemeral that is.

I hear young women all the time talk about diets and bikinis and fat thighs. I want to tell them they should enjoy themselves now and forget all that—there’s plenty of time for self-absorption and depression. Why start so early, and at the top of your game?

I don’t mean to sound preachy. But I wonder what we achieve by torturing ourselves this way.

My mother has been on a diet since I was a child. None of them has worked for more than a couple months. She’s spent decades trying to reach a place that was apparently off-limits to her from the beginning.

She weighs the same now as she did when she was 40—maybe a little more. And she spent all those years dieting, feeling deprived, frustrated and exhausted. For what?

I feel sorry for all the women who stand in front of the mirror, turn sideways and hold their stomachs in; all the women who buy jeans that don’t fit so they’ll have a goal to reach; all the women who turn down delicious food because they’re afraid to have an appetite. I myself actually spend hours each month being gloomy because I’m an apple shape instead of a pear.

Hence my message. Young women, you look wonderful—all of you. Please don’t spend your time criticizing yourself. Please understand that time is short. Enjoy your beauty now, because before you know it, you’ll have an age spot where your nipple should be. And that, as I used to say ad nauseam in my 20s, is wack.