Gym class is what broke me.

The other day, my wife and I were talking about our daughter's impending first week of kindergarten. We were discussing her schedule, and my wife mentioned that my daughter has gym class twice a week.

That stopped me. Gym class? Gym class! My daughter was going to have gym class. It's official. She's starting school this week. Not preschool. Not pre-K. School school. Real school. School with a bus ride, and lunch, and gym class.

I thought I was cool with my daughter starting kindergarten.

I'm not cool. I'm a disaster.

I'm more anxious than usual. I've had a shorter temper with my her lately, and I think there's a direct correlation . I find myself getting nervous on her behalf.

My kid? She's stoked. She gets to ride the bus. She gets to buy her lunch, which is the coolest thing to happen to her world in a long time. She met her teacher the other day, and she's already been pegged as one of the classroom helpers.

I thought I'd be cool with all of this.

I'm not cool with it.

I'm that parent, the one I never wanted to be or thought I would be. I'm the one wondering where the hell the past five years went. I'm the one wondering what happened to my baby.

It feels like the fundamental nature of our relationship is changing. I was lucky. She was born while I was finishing up my master's thesis, so I was a stay-at-home dad for the first eight months of her life. I was in grad school until she was almost four, and I teach, so my schedule is flexible. I've been home with her a lot.

We've been a team — me, her and her mama.

Now, that's changing. Now, she's starting school. Not preschool, but school school. She's starting a new life, a new routine, joining a new team. And where does that leave me? Where's that leave me and her mama? It's preposterous, but that's kind of what it feels like.

It leaves me sitting here, looking at the calendar and wondering where the summer went, where the last five years went, where the next 13 years are gonna go. My daughter's starting school, and I'm not cool with it.

But ...

She's cool with it.

She's ready. She's a little bit nervous but a lot bit excited.

In a lot of ways, she's starting her life now. She's starting real school, which is a big deal, and it's awesome. My being sad or upset this week has nothing to do with her and everything to do with me, with my nostalgia, with my wish to slow time down a little bit.

But time doesn't slow down. It shouldn't. All the good stuff is next.

My daughter starts school this week. School school. And she's super excited.

And that? That I'm cool with.