At 67 years old, former film industry executive David Kirkpatrick hadn’t run like a kid since he was — well, a kid. And it never occurred to him to try until last year, when a friend on Facebook asked: “Have you ever just full out run like you were 5 years old again?”

It sounded crazy to Kirkpatrick, who until then had been counting steps on his FitBit (he once logged 100,000 steps in a day). But he decided to give it a try.

“I was afraid to do it initially because it was something I hadn’t done in so many years,” said Kirkpatrick.

Despite his fear, Kirkpatrick walked onto his farm in rural Massachusetts, picked up a soccer ball, kicked it a few hundred feet, and chased after it as fast as he could.

At first, he says, it felt “horrible.”

Unlike long distance running, which is an aerobic exercise, sprinting is anaerobic, which means Kirkpatrick’s body was moving at such an intensity that his cardiovascular system couldn’t deliver oxygen to his muscles quickly enough.

He had trouble catching his breath, he recalls, and his body felt “traumatized.”

“It was unsettling, it was different, it wasn’t something I really knew,” he recalls. But he says the soccer ball made it fun.

“That visual representation of a colorful ball in the grass — whether it’s in the city park or the countryside — it just made me feel like I could do it,” Kirkpatrick says.

He says sprinting wakened up his endorphins. After about an hour, he started to feel upbeat. “I found myself feeling confident. I felt a different life in my step, and felt so good after that.”

Sprinting has since become a go-to exercise for Kirkpatrick, a regular contributor for Better Humans on Medium.com. And it’s helped him lose a “whopping 40 pounds,” he says.