Jensen Huang's biggest career lesson didn't come from a mentor or a fellow tech CEO. It came from a gardener he met while traveling internationally.

"I used to work from one of our international sites for one month each summer," Huang, the billionaire co-founder and CEO of computer chip company Nvidia, said during a commencement speech at the California Institute of Technology on Friday. "When our kids were in their teens, we spent a summer in Japan. [One] weekend, we visited Kyoto and the Silver Temple."

While there, Huang came across a man working in a vast garden. The day was "suffocatingly hot, humid and sticky," he recalled. But the man diligently tended to the moss despite the sweltering heat. He used only a bamboo tweezer to sift through the foliage, which initially puzzled Huang.

"I walked up to him and I said, 'What are you doing?'" said Huang, 61. "He said, 'I'm picking dead moss. I'm taking care of my garden.' And I said, 'But your garden is so big.' And he responded, 'I have cared for my garden for 25 years. I have plenty of time.'"

Their interaction was brief, but the gardener's words became one of the "most profound learnings in my life," Huang said. "It really taught me something. This gardener has dedicated himself to his craft and doing his life's work. And when you do that, you have plenty of time."