What’s Powering 3 Generations of Runners? Family, Grit and Sandwiches.

On Sunday, Rodrigo Villavicencio is running his 20th New York City Marathon. His son, James, is running his ninth. And for the first time, his grandson Justin is joining them.

“The New York City Marathon, it’s incredible,” Rodrigo, 78, said. “I cannot explain it to you — now especially, running with my family, my grandkid.”

James, 55, was the first of the family to take up running, finishing his first New York City Marathon in the late 1990s. He encouraged his father to try it out and the two have run several city marathons together since.

Justin, his brother and their sister — 22-year-old triplets — grew up cheering from the sidelines in matching shirts that read “GO DAD GO,” or “GO PAPA GO,” using their nickname for their grandfather.

In the weeks before race days, Rodrigo’s wife, Lupita, has even taken to hand-sewing her husband’s and son’s names onto their shirts, so strangers will be able cheer for them personally.

On Sunday, she and the extended family planned to travel from Long Island to cheer. But only Lupita, following a detailed map and time table, was going to Brooklyn, Queens, Manhattan and the Bronx to meet and support all three runners at multiple spots along the route.