The founder of a $600 million company shares the advice from Jamie Dimon that shaped his career

Jim McCann could talk for hours about his company, 1-800-Flowers.

He started with a single flower shop in 1976 and took it to a business with a market capitalization of around $600 million.

But he learned back in the 1990s, when 1-800-Flowers was taking off, that he needs to keep his monologues short if he's going to motivate his employees. It's a lesson he learned from his friend and fellow Queens native, JPMorgan Chase CEO Jamie Dimon.

"I remember one time he said to me, 'Jim, you spend way too much time evangelizing,'" McCann told Business Insider. McCann asked Dimon what he meant. "He said, 'You want everybody to get it. And everybody doesn't need to get it. Everybody can't get it. All you want them to do is understand that you get it.'"

Dimon was at Citibank at the time, and McCann said Dimon explained his point further: "For example, we're surrounded by smart people here at Citibank. There are only smart people here. But I would tell you that there's probably not a half a dozen people who really understand how we work and how we make money. If I spent all my time and energy trying to evangelize so that every one of the 180,000 people here get it, I'd be exhausted and unproductive."

McCann said that his brother Chris, who took his role as CEO of 1-800-Flowers at the end of June, still regularly reminds him of Dimon's advice. "He'll say to me, 'You're evangelizing! There's no need!'" McCann said, laughing.

McCann, who still has a hands-on approach with 1-800-Flowers, told us he was recently working with a group of his company's engineers developing tools for the site when he found himself explaining in-depth the ethos of the "celebratory ecosystem" he was creating with 1-800-Flowers and its partner companies.

Chris called him out for his speech.

His brother told him, he said, "Look, they're engineers. Tell them what you need them to build. They want to understand that you get how it fits into the big picture, but they don't need to know. And you're wearing them out."