Serena Williams spoke candidly about the pressures that her superstar career in tennis occasionally puts on her personal relationships.

Speaking on the latest episode of Wondermind’s podcast, The Business of Feelings, the tennis sensation opened up about how success in her field isn’t always all it’s made out to be.

“It definitely can be lonely at the top. In particular, tennis,” she said. “People don’t realize how many hours you spend by yourself. So much so that it was hard for me in a relationship, because I am so used to being alone every single minute and day of my life that it’s like, ‘Well, I can’t even be around people.’ And a lot of people don’t realize that.”

Williams married Reddit cofounder Alexis Ohanian; together, the couple share five-year-old daughter Alexis Olympia Ohanian Jr.

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“So you get this celebration and it’s, like, great, but behind closed doors, the life is different because you also have to live your life, whether going outside becomes a problem because there is no privacy,” Williams continued. “But all that stuff is great, because if there is no privacy, that means you’re successful, and that’s kind of what you want, but it comes at a cost, right? And it’s worth the cost if you think it is. But there is always a trade-off.”

Serena Williams and Alexis Ohanian at the 2019 Met Gala. Photo: Jamie McCarthy / Getty Images

Last year, Williams talked about what it takes to create a lasting marriage while participating in a rapid-fire Q&A for Bumble.

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“Marriage is not bliss. But it can be if you work at it,” she said. “A dealbreaker for me in a relationship is definitely loyalty. Well, not having it, that is.”

This article originally appeared on Harper’s BAZAAR US.