My father died on 9/11. I wish I had him today, for more reasons than I ever thought I would.

My father loved to fix stuff. And he loved to learn how. Whenever we had work done on our house – I remember several big renovations – my dad would follow the workers around. Not to keep an eye on them, but to learn from them. He was forever curious.

He tried to pass on any newfound home-maintenance knowledge to me. But I was a teenager, and you know how teenagers can be. Learning to fix a house just wasn’t a priority. So maybe I’d listen a little, but then I’d run out to see my friends or watch the Yankees.

But now I’m a father myself with my own house and I wish I had listened. Turns out, if you can’t do the work yourself, you have to pay someone else to do it. And that can be expensive.

I wish I could ask my father now, but he was killed on Sept. 11, 2001.

My dad, Joseph Leavey, was a lieutenant in the New York City fire department assigned to Ladder 15 in the South Street Seaport. His unit was the “second-due” at the towers. He was one of 343 firefighters who died on that awful day.

I have a 5-year-old daughter, Kaia, and a 3-year-old son, Joseph. And on Father’s Day I find myself thinking of all the things my father and I couldn’t share in the last two decades.

I’d probably have him over to my house every day: How do you fix this? What do you do here?

Growing up without him, especially in those tricky teenage years, was like living with an empty space beside me. There were the big moments when his absence was especially obvious – graduation, new job, marriage, children.

But to me, as I’m coming to learn, fatherhood is also about those little moments that go unmentioned and unphotographed. And today those are the moments I choose to remember, and the moments I hope my own children will treasure when they think of me.

My dad was an engineer before he was a firefighter. He loved to do stuff like explore the city’s subway tunnels. In one of life’s truly heartbreaking ironies, he was especially fascinated by skyscrapers. He watched the World Trade Center go up with a child’s awe and amazement, and an engineer’s interest in how those towers were constructed.

When I was a kid, we were a team. I remember our vacations in Florida. My dad and I loved the rollercoasters and water rides. My sister was too little for them and my mother, well, she just couldn’t be bothered by the rides. But not dad and me. We’d finish and get right back on the end of the line to go again. We’d run from coaster to coaster to squeeze in just one more thrill before closing time.

He taught me to ski. I was small for my age, and he’d set his skis in a wedge and then hold me with one foot on each and we went down the "bunny" hill. This was all fine and good until the time he lost his balance and fell on top of me, which is still a favorite family story.

He encouraged me to try stuff, but never too hard. My dad would always come to my games – soccer, baseball, basketball. I was usually one of the smaller kids on the team, but I loved playing sports, just like he did at my age. Dad always encouraged me to try everything but if I wasn’t having a good time, he didn’t push me to keep doing it regardless. He wanted me to be passionate about what I was doing, and to have fun.

Now that I’m a father myself, I try to be like him. I’m not going to push my children to play baseball seven days a week if it’s not their passion. I’m going to find the thing we both enjoy – rollercoasters, I hope – and revel in running right back to the back of the line after a ride is done. But if Joseph or Kaia don’t like rides, I’m not going to force them. We’ll find something else.

This has been such a tough year for everyone, and I wish I had Dad around to talk about it. COVID-19, restrictions, vaccinations, politics. I see with each passing year how similar we are. And that space is never filled. I still keep his badge with me for good luck at a big event like the birth of our children or a presentation at work.

At least those of us who lost parents on Sept. 11, 2001 – there are 3,051 – have a community that understands this empty space. I’ve tried to be a mentor to children growing up fatherless. I’ve found my involvement with a group called Tuesday’s Children that provides support to the families of victims of Sept. 11 and terrorism; it gives me a chance to put my complicated feelings to good use.

Life is a circle, isn’t it? My wife, Larissa, is from Miami, and while she was willing to give skiing a try for me, let’s just say it’s not in her DNA. I haven’t skied for years, even though I love it. But Kaia is almost ready to learn, and I can’t wait to try with her.

I’ll just be sure not to fall on top of her.

Brian Leavey, a director at BlackRock financial management, mentors fatherless children with Tuesday’s Children, a national nonprofit organization serving families and communities impacted by terrorism, military conflict and mass violence.

This article originally appeared on USA TODAY: Father's Day: My dad died on 9/11. Now I'm a dad myself.