Round Rock grandfather-granddaughter duo will run Boston Marathon as rare entry

“This was an opportunity I couldn’t pass up,” Mia said.

Round Rock resident Carlos Sanchez, left, puts on his shoes next to his granddaughter Mia Sanchez. They will run the 2026 Boston Marathon as that event's first documented grandparent running with a grandchild after both had qualified. (Carlos Sanchez)

In the first marathon of her life, she clocked a time of 3 hours, 14 minutes and 26 seconds, which was a full 11 minutes under the standard she needed to qualify for Boston for 18- to 34-year-olds. Carlos, meanwhile, was on his 36th marathon and ran 15 minutes under his 65-69 age group standard to finish with a time of 3:50:49.

“That’s one of those moments that’s seared in your mind,” said Carlos, who’s now 67. “You hug each other. And you tell each other: We’ve Boston Qualified.”

The duo will line up Monday at the 130th running of the Boston Marathon alongside roughly 30,000 participants from around the world. Only there’s one more note to this story: they’ll be one of the rare grandfather-granddaughter duos in the race’s history.

“It’s an honor to have this opportunity to run with my grandpa,” Mia said, “because it’s something I’ve always dreamed of, and I know how important it is to him.”

Record or not, history is history

While Carlos is hopeful this is the first instance of a grandfather and granddaughter running (and qualifying for) the Boston Marathon in the same year, the chances aren’t likely. Since 1972, when women were first allowed to run the historic race, fathers, mothers, sons, daughters and grandchildren have been competing in Boston — accounting for literally millions of finishers.

That being said, record-keeping is important. And for Carlos, a former computer programmer and system administrator who retired last June, history has not accounted for this special kind of family relationship just yet.

“It’s hard to find something like this,” he said. “It’s unique.”

To Carlos, these are the types of stories that we tell each other as we get older.

Finding his passion late in life

Carlos was 50 when his relationship with running began. Back then, he knew almost nothing about the sport. His daughter, Alexis, who had run in high school and for a time in college, taught him how to properly tie his shoes — the “runner’s loop,” as it’s commonly known. That same year, they ran their first marathons in Chicago.

Soon enough, running became Carlos’ passion. He racked up 37 finishes in 12 states, including places like Kansas City, Juneau, Alaska, and Athens, Greece. He’s been fortunate to have been mostly been injury free, save for that one time in 2023 when he crashed his bicycle during a 150-mile ride.

Safe to say, Carlos doesn’t ride much anymore. But you want to know the first thing he did when he was healthy?

Naturally, he ran a marathon.

Actually, that’s when he ran the Mountain 2 Beach Marathon in April with Mia.

Bonding with Grandpa all over again

There has never been a time in Mia’s life when her grandfather hasn't been in the picture. Whether on the cross-country course or on the track, Carlos has always been there. With a sign. With a calming word. Always with his camera for a picture or two. At postseason awards banquets, Mia said, he would sometimes create slideshows showcasing finishes of her and her teammates.

“It got to a point where everyone on my team — middle school, high school or college — knew him,” Mia said. “He wasn’t just my grandpa. He was everyone’s grandpa.”

When Mia finished her eligibility and graduated from St. Edward’s in 2024 with a degree in environmental biology and climate change, she headed off to Harvard. Running became harder. Some of the love was lost. “At the time, I was running very passively,” she said.

This marathon journey became their connector again. Mia had just eight weeks to train for the debut race in California. It wasn’t an ideal spot for anyone. But what helped was institutional knowledge and years of miles under her legs.

“There were a lot of times I would go to class, have an hour for a lunch break, then I would go for my runs, shower, then go to my next class,” said Mia, who’s working toward a master’s degree in environmental health at the Harvard T.H. Chan School of Public Health.

A run of a lifetime for grandfather, granddaughter

In Ventura, Calif., the pair took the same bus to the starting line. Carlos remembers the stillness of that moment.

“We’re sitting there and anticipating it,” he said. “I’m looking at her thinking, ‘OK, I know what she’s about to experience.’ Sitting there in the dark, being with her, it was so incredibly touching and special.”

When they walked out to the starting line, Mia began to cry.

“That was the moment that hit me,” she said. “I’m about to run 26.2 miles. It was happy tears of excitement and nerves. But he was there next to me. It was great to know we were together.”

Right before the race set off, Carlos turned to Mia and said he was proud of her.

Next up: a date with the Boston Marathon

Last July, Carlos traveled to Juneau and ran his 37th marathon in a new personal record of 3:50:19. The stark environment around him was unlike anything he’s ever experienced.

“The mountains, the glacier in the distance,” he said. “The scenery, the temperature. There’s bald eagles everywhere. It was just so different.”

That race continued a path he started in 2008, one that’s seen him cover thousands of miles. He still runs about 40 miles a week on average and doesn’t seem himself stopping anytime soon.

Mia, on the other end, has run a high of 52 miles over her marathon build and has done three long runs of over 20 miles each. She also earned a small social media partnership with Lucille Health to tell her family’s story of connection — a $1,500 deal that will see her post reels and stories of her and her grandpa.

On Monday, they’ll ride the bus together to the start line. The point-to-point course begins in the small town of Hopkinton before it makes its way toward downtown Boston, finishing on a jam-packed Boylston Street. Thousands will pack the area, bringing nonstop energy.

Carlos has been dreaming about this all his life. It took him 36 tries to get there.

“I didn’t believe it was possible,” he said.

For what it’s worth, Mia never doubted him.

It was his encouragement that helped redefine her relationship with running and this new pursuit in the marathon. Mia is graduating soon, and the real world awaits.

But running? That’s going nowhere. And she has her grandpa to thank for that.

“All my life, he’s the one who supported me through running,” she said. “He’s a big motivator in my training. I get to have this moment with him.”