Some think of joy as the sound of a baby’s laughter or the look of wonder on a child’s face on Christmas morning.

On my planet, joy is removing the belt from your pants after a hard day’s work and realizing I accidentally put on the belt of my 14-year-old daughter that morning— and it fit!

Not only that, but I wore it all day and had no trouble breathing or walking down stairs. I didn’t even have to unbuckle it after wolfing down a lunch of Lean Cuisine, Diet Coke and six peanut-butter, chocolate-chip cookies.

I trembled at the realization that I existed, even for one day, in the belt of a size 1.

Since I began losing weight a year ago, I have joked with my daughter Shannon that we soon would be wearing each other’s clothes. It’s every mother’s dream — not only to be the same size as her daughter, but to have her clothes deemed stylish enough to meet a teen’s standards.

But with me still a size 10, it seemed an unattainable dream, an unreachable star, a preposterous, unachievable utopia. More unrealizable, I thought, than my dream of living on an island populated only by Orlando Bloom and trees that drip chocolate.

Now it’s closer than I thought possible. Sharing a belt was only the beginning.

Soon the joyous day dawned when Shannon hollered: “Mom! I don’t have anything to wear under this shirt and it’s too low cut.”

I realized the size-medium black tank I wear under low-cut tops would fit her without falling off. Heart racing, I grabbed the shirt and handed it to her. Trying to sound casual, I said, “Here. Try this.”

I waited, breath held, until she emerged from her room wearing the tank beneath her top.

“Thanks, Mom,” she said.

Tears sprung to my eyes. Without realizing it, my baby had just made her mother’s millennium. She had borrowed my clothes.

Never mind the top is so tight on me it rides up above the muffin-top created by my gut when the waist of my pants is too snug. Never mind she was wearing it under another top so the fit didn’t have to be the best.

She was still dressed in my clothes for the very first time.

It was a moment. No one can take it from me.