Griffin Mazeski decided to run America’s Finest City Half Marathon in San Diego to celebrate his tenth birthday, but in his waning hours as a 9-year-old, he still had business to tend to. And, the results are well worth celebrating.

That’s because the Colorado boy set a new world record when he ran the 13.1-mile race in 1:33:43. It becomes the fastest time ever recorded in the distance for a 9-year-old.

According to the Association of Road Racing Statisticians, the previous record was held by Liam Ballard, who was nine in 2015 and ran a half-marathon in St. Petersburg Beach, Florida in 1:34:59.

Griffin toed the start line with his parents and sister, according to Denver’s 9News, and felt great throughout most of the race. He even out-ran his father, who had to dial it back once Griffin found a new surge of energy.

“It was pretty hard and I didn’t know if I could really break the record because I didn’t feel that prepared coming into it,” said Mazeski, who is from Aurora, Colorado. “The first 11 (miles), I mean, I felt really good and I was going under my pace that I wanted and I felt really calm and I could breathe easily, but at mile 12, there was a really long hill and I sort of died out on that.”

Once the father-son due reunited at the finish line, it was all smiles.

“I was really excited that I met my goal,”Griffin told 9News. “It’s just hard to think, but I felt crazy good.”

What a way to ring in double digits.

Way to go, Griffin!