There are days when I wake up and think that I might, just maybe, still be 15 years old. I know I have children and responsibilities. But that doesn’t always seem to stop me from thinking that I’m not that different from a 15- or 20-year-old. It turns out I am not alone in this kind of magical thinking. Many people in their 30s, 40s, and 50s whom I’ve spoken to said that having children and jobs didn’t necessarily always make them feel so grown up all the time.

But then there are those moments when life serves you a large helping of reality.

Sometimes these moments are predictable: You’re up all night with a sick child; you’re not sure how you’re going to pay the bills; you don’t think your marriage is going to make it.

And sometimes reality sneaks up on you when you least expect it. My most recent I’m-not-15-years-old-anymore moment came a week ago, when I took my boys to a 90,000-square-foot indoor water park in the Poconos. We were using the hotel as a base so that we could visit my 92-year-old grandmother, who lives nearby in Scranton, Pa.

Jacob and Josh’s mouths dropped open when they caught their first glimpse of the water park inside the Great Wolf Lodge, a 400-room family resort 90 minutes from the city. When they learned that the hotel also has an arcade, a live-action video game running through the corridors, and a Pizza Hut, Jacob asked me if we could move in permanently.

Since we only had a few hours to play around before we needed to leave to see my grandmother, we quickly checked in and changed into swimsuits.

This is going to be great, I remember thinking. I love waterslides, and what could be more fun than going on waterslides with my boys?

Well, it turns out that I loved waterslides — emphasis on the past tense. After a couple rides, my contact lenses bothered me. My back ached from lugging the tube to the top of the stairs, and while my boys were literally jumping up and down in anticipation — giddy from the water roller coasters, plunges, and flumes — I was wondering just how many more slides I had to go on before I could respectably retire for the day.

The truth was clear: I was no longer 15 years old. And I found that I loved new things about the experience. I enjoyed snooping around the concession stand and figuring out what we were going to have for a snack. I wanted to take a peek inside the water park store to see if they had any cute bathing suits for the gang. And more than anything else, I just wanted to sit and watch the boys while I read the weekend newspapers.

But when did I become that mother who watches her children go down the waterslides? Wasn’t that the parent I vowed I wouldn’t be? I was the mother who had climbed inside the McDonald’s PlayPlace tubing to retrieve a crying child. I was the one who dragged my boys down white-water rapids, hiked to the tops of mountains, and took my crew sledding even when they didn’t want to go.

I decided that I was not ready to turn in my stripes — even if my body ached and my contact lenses had to be thrown out. But the point was made, loud and clear. I might not want to be the parent who sits on the sidelines. But I am not 15 years old anymore.

During the July Fourth holiday, a family-filled weekend, I left my 5-month-old child for a half hour with my aunt, who is as youthful as a nearly-59-year-old can be. I had only meant to leave the baby for 10 minutes, but I got caught up talking to a cousin I hadn’t seen in a while. When I returned to my aunt, she handed me back the baby and, for my mother’s entertainment, collapsed in exhaustion on the couch.

“Are you kidding me?” I howled with laughter. “Your grandchildren are a decade away. You’d better stay young.”

She admitted to putting on a bit of a show, but said that you never really know what it feels like to be a certain age. “Until you’re actually there, you just can’t imagine what your reaction will be,” she said.

sarasberman@aol.com