Serena Williams has made the extra effort to detail the difficulty of motherhood. While speaking at JPMorgan Chase event in New York City on Tuesday, the 23-time Grand Slam champion said the best advice she got about taking care of herself and her baby made reference to the instructions flight attendants give onboard an aircraft.

The tennis phenom recently pulled out of a tournament to spend more time with as a mom. She even spoke about the struggles of motherhood and dealing with postpartum depression. However, according to The Undefeated, Williams said her trainer, Mackie Shilstone, advised her to not feel guilty about taking care of herself before he 11-month old daughter, Olympia.

“He told me a baby is like a plane,” she said. “When you’re in the plane, the people tell you to put on your mask first before helping the person beside you. And I realized I wasn’t putting on my mask first. I was constantly putting on — I was putting on her mask. It’s a hard thing to process. I’m still learning that.”

Williams is scheduled to compete at the US Open next week wearing outfit designed by Virgil Abloh for Nike.