This week at the US Open Serena Williams drew attention to sexist rules governing women’s attire by wearing a tutu on the court. It turned out this was the perfect outfit for her final match. 

The referee penalized Serena for looking to her coach in the stands. Serena was outraged that he’d accuse her of cheating. He penalized her again. She protested that he penalized her for being as angry on court as men are. Fans agreed, and protested loudly. Men rarely get penalized for what Serena did. She told the ref he was sexist. She called him a liar and a thief. At one point she was so frustrated that she smashed her racquet to pieces. Even with vocal support of the crowd, she lost the match.

Serena has been heartbreakingly transparent about the difficulties of her post-baby return. Unfortunately we rarely see that from women. Mostly we see BS like Sheryl Sandberg’s arrogant, misguided battle-cry for new moms to lean in. Serena is a perfect example of what it’s like to lean in. She is both a fortune-teller to women who are about to go through this phase of life, and she’s a mirror for the rest of society to see what’s really going on.

The precondition for going back to work is money and expertise. Because even though you have a new baby, the family will revolve around you. You need to have married a spouse who has already proven himself so he’s on-board to support your career. And you need a career that is special enough to warrant the whole family operating around it. And you need a lot of money to hire a nanny.

If your spouse is still trying to prove himself, you’ll divorce. If your spouse won’t be the primary caregiver, you will think your child deserves a parent as the primary caregiver and you’ll opt out, which is what nearly all high-performing women do.

All women can re-enter the workforce where they left. There is an enormous shortage of women over 35 in professional positions. Because professional women leave the workforce after having a baby. If you want to be full-time after you have a child, you will have no problem getting your job back. The real question is: do you like your job enough to give up your time with your baby in order to do the job?

Serena has been candid about how going back to a pre-baby job after becoming a mother is exhausting and forces difficult compromises. And remember this is not what it takes to build a career, it’s what is required to just hold on to the place you’ve already earned.

Patience for workplace BS disappears. Serena has faced gender discrimination over and over for decades, and she’s handled it with incredible grace.  But things change when you have a baby. Every second you devote to your work is time away from your baby, so you want your time at work to matter. You become acutely aware of the moments when people at work undermine your efforts.

Serena lost her shit on the court yesterday because her time feels more precious now; she could brush off anything before she had a baby. And thanks to how transparent she’s been about the difficulty of coming back to work, we are not surprised she can’t brush it off anymore.

Work doesn’t make people happy. Jennifer Senior’s research-laden book explains why having children does not make people happy, but children do create the most rapturous experience available to adults. Women feel this acutely, which is why women leave the workforce for kids and men don’t.

You will not climb up a ladder when you have young children, you will work twice as hard just to stay where you are. If you don’t like where you were when you had the baby, it’s not worth going back.

If you do want to go back, you will be shocked by how much harder you have to work than all the men at your level who have stay-at-home wives. You can do it, but it will be lonely. This is why very few professional women continue their career after a baby, and the idea of leaning in has been met with ridicule.

Sonja Lyubomirsky published a paper showing that happiness is a cause of career success rather than a result. Take heed. Be very clear on what you gain by returning to work. And for some time I have wondered, what are Serena’s career goals now?

At the awards ceremony the crowd continued its boisterous protest. Naomi, the first-place winner, pulled down her visor to cover her tears. Serena turned to check on her, and she noticed the tears, so she put her arm around Naomi’s shoulders. That’s when I realized Serena has come back because she’s not done clearing the path for the women who come after her.

Which is why Serena’s a winner today. That picture of Serena and Naomi is the picture of Serena’s hard-won return to tennis so she can force more change. And I hope someone saved her smashed racquet, because that one belongs in a trophy case.