I’m turning 40 on Wednesday. I don’t want to turn 40. I’ve been depressed about it since I turned 38. I keep waiting for some grand stroke of wisdom and peace to overcome me, but all I feel is irritable and bewildered. Mostly irritable.

I poll everyone about aging. Children, Safeway clerks, ancient relatives, psychoanalysts, New Age friends, garbage men, the whole gamut of humanity. Children say, “40 is old. Duh, stupid-head.” Everyone else says some variation of, “40 is young! Age is just a number! Besides, it’s better than the alternative! Wait till you turn 50! It’s all about attitude!”

Only the psychoanalyst spoke the truth: “40 is the beginning of an endless slide into decay, culminating, mercifully, with death.”

That seems about right to me.

I wasn’t happy about turning 30, either. I felt like the era of blissful irresponsibility was folding. The world forgives you for walking off a job at 25, but at 35 it’s sort of unbecoming. Actually, you can do anything at 25 — bounce checks, move every two months, stay out until 4 a.m., eat nothing but popcorn and never exercise. I mourned the end of that life, deeply.

To cope, I went to the city on my birthday and drank so many vodka-cranberries that I passed out until I was 33. When I came to, I had a husband, two kids, a house, a Subaru station wagon and a 100-pound dog.

I still have the kids.

They’re actually the ones making me feel especially decrepit right now. The other day I asked a male friend, “Do I look really old and unattractive?” He squinted at my hopeful face and said, “No! Not at all. You just look … uh … tired.”

I raced to the mirror and stared at the Samsonite bags under my eyes, the Grand Canyon-like wrinkle between my eyebrows, the accordion lines around my eye sockets. Boy, am I tired! I’m tired because I had to get up at 6 a.m. to make three lunches, three breakfasts, find six matching socks, six shoes that might or might not fit, locate last night’s half-completed homework and get the munchkins to school before the “tardy” list is in.

Then it’s off to work, praying the newspaper industry lasts another day, then the nightly race through traffic to retrieve my children before getting billed the $1-per-minute late fee at Happy Time After Care. Then it’s dinner (assuming there’s food in the house, otherwise it’s another night at Sparky’s Giant Burger), homework (crapshoot), baths (rarity) and, if God is smiling on us, bedtime before 10 p.m., no default notices from the bank and no bloodshed.

Of course I have wrinkles! It’s a miracle I’m not institutionalized. But the thing is, I don’t want wrinkles. I don’t want to get old, and I really, really don’t want to turn 40.

When I was a kid, my dad had a clipping from New West magazine on his liquor cabinet. The headline was, “Things I Have Learned After a Half Century of Living.” No. 1 was, “Liquid shoe polish doesn’t work.” No. 2 was something about staying mellow.

I thought, maybe I should make a list of “Things I Have Learned in Four Decades of Living.” I sat down at the dining room table with a pen and paper.

No. 1. Parking tickets do not go away if you put them in the glove compartment. In fact, they multiply.

No. 2. Stay away from anything big and stupid (i.e., horses).

No. 3. Expensive coffee is worth it.

No. 4. Um … um …

I actually have learned very little in four decades of living. When I was about 28, I knew everything, but alas, much of it proved to be untrue.

When I was 28, I thought it was better to “age gracefully.” I thought people who dyed their hair were failing to embrace the full spectrum of life, and worse, buying into the sexist myths of a youth-obsessed culture.

That was before the Grand Canyon grew between my eyebrows. Now I can easily envision myself as one of those frightening 80-year-olds with jet-black hair, crimson lipstick and a face immobilized by plastic surgery. Smug 28-year-olds will circulate my snapshot around the Internet.

Meanwhile, I’m not sure what I’ll do on Wednesday. Lock myself in a broom closet, possibly. Start lying about my age. Self-medicate. Discover Jesus. Let myself go. Weep.

I can guarantee one thing, though: I will not be going gently into that good night. There will be a lot of Botox before it’s over.

E-mail Carolyn Jones at carolynjones@sfchronicle.com.