The little girl on the screen hopped over small waves as they rolled in to shore, her blonde ponytail bouncing as she laughed.

Still smiling, she held out her arms to her mother, silently begging to be spun around.

The young mother smiled back, then took the child’s hands and twirled, spinning the small body above the waves until both were dizzy.

I smiled at the images on the dusty videotape, which I discovered last Sunday afternoon, the day my daughter Shannon turned 13. Shannon reconnected our old VCR and pushed in the unlabeled tape, then we sat cross-legged on the floor to watch the images of our trip to the beach when she was 3.

Shannon hadn’t begged me to spin her in many years and, just as I could no longer fit into those size 8 shorts I saw on the screen, I couldn’t easily lift her if she asked.

A lot changes in 10 years.

People love to say about children, “They grow up so fast.”

“It goes by so quickly,” we tell any new parent who will listen.

I don’t know why we bother.

That fact of life is one of many we can’t truly grasp until it happens to us.

It dawns in stages, creeping into our brains in the minutes a child first walks across the street alone, shares secrets with someone other than us, and goes to friends for advice.

But the actual moment of realization that years have slipped by does not creep, it comes crashing in.

Mine came about six months ago when I was sitting on the sofa on a lazy Sunday afternoon, a fire crackling nearby. A favorite movie of Shannon’s and mine was on television.

“Come watch with me,” I called to her in her bedroom.

Hearing no response, I called: “Come on, Shannon, watch the movie with me.”

Her door opened a crack and she hollered back: “I’m on the phone, Mom. Be out in a minute.”

Many minutes ticked by. The movie ended. She didn’t come.

Often these days, I’ll catch myself asking Shannon to turn off the computer, or get off the phone, so she call tell me about her day.

Not so long ago, she would ask me to sit beside her and watch TV, or hang up the phone and talk to her.

Often, I would. But sometimes I would tell her I was busy cleaning the kitchen or folding the laundry, or writing.

Sometimes, I’d get a call from work during a movie, and she’d roll her eyes and hand me the phone. I’ll be done in a minute, I’d tell her.

I usually wasn’t.

Now, she wasn’t growing up so much as growing away.

Like any parent, I want my child to be independent, to learn to make decisions and be responsible. I want that for her as much as I ache for the afternoons spent sharing popcorn and Twizzlers at the movie theater, watching whatever happened to be playing because we wanted to sit side by side in a dark, cool theater and experience a little magic together.

In the years before Shannon turns 18, as she is learning to be herself, I’ll need to relearn how to be someone other than the mother of a dependent child.

But not just yet.

As I sat at the computer the other night, playing a card game and talking on the phone with a friend, Shannon came and tried to sit on my lap. It was a small chair, a small space between me and the computer desk, and I was mildly annoyed.

Then I heard her, as loudly as if she’d spoken: “Spin me, Mommy.”

I hung up the phone, pushed back from the computer and opened my arms to welcome her. Then I tickled her until we were red and breathless from laughter.

We all, as parents, miss too many moments because life gets in the way, but I’ll treasure this one as if it had been videotaped.

After all, they grow up so fast.