The key success lesson Reddit co-founder Alexis Ohanian learned from fiancée Serena Williams

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Alexis Ohanian, the co-founder of Reddit, says there's one thing he admires most about his fiancée Serena Williams, who is widely considered to be one of the greatest athletes of all time: her intense work ethic.

Ohanian, who recently announced that he'll be taking a six-week paternity leave to care for the couple's baby due in the fall, spoke with Vanity Fair's Buzz Bessinger for a cover story on their romance.

Alexis Ohanian will take parental leave to be with fiancée Serena Williams and new baby

Notably, Ohanian's decision to propose to Williams came "not simply out of happiness or compatibility," writes Bessinger. "She was helping him become the best version of himself because of her own work ethic and focus."

The Vanity Fair piece continues:

He thought he worked hard — it is part of the romance of high tech that everyone works 18 hours a day and then curls up under the desk for a few hours' sleep with their laptop as teddy bear and pacifier — but he realized it was nothing compared with Serena.

"I felt like a door had been opened to a person who made me want to be my best self," says Ohanian. "I find myself just wanting to be better by simply being around her because of the standard she holds."

Ohanian's sentiments about Williams make sense. The 23-time major title winner, who in January won the Australian Open while pregnant, discussed her desire to be the best version of herself with Glamour in an interview last year.

Here's how tennis superstar Serena Williams has built a brand off the court

"I try to be the best that I can be every day," she says. "I have bad days. I had a bad day the other day. I hit for only, like, 30 minutes, and I stormed off the court. But that was the best I could do on that day."

When asked whether or not she's the world's greatest athlete, Williams' response is measured. "So am I the greatest? I don't know," she tells Glamour. "I'm the greatest that I can be."

She adds, "If I'm not playing well, I do get down on myself because I am a perfectionist."

Williams doesn't only exhibit prowess on the tennis court. She's also been highly successful as a businesswoman with a number of ventures from tech to fashion.

Soon, both Ohanian and Williams will have their hands full with a different task: raising their first child.

"She's very good at a lot of things," says Ohanian in a recent interview on CNBC's "Squawk Box," "and well on her way to being an awesome mom too."

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