Fans and supporters call her the GOAT (greatest of all time). Whether or not you agree, it’d be tough to argue she hasn’t had an impact on women’s tennis and what it means to be an athlete, period. Her 27-year professional career is one of the longest in her sport’s history. And the mental toughness she’s consistently displayed throughout the decades is certainly noteworthy, says Eric A. Zillmer, PsyD, a licensed clinical psychologist and the Carl R. Pacifico Professor of Neuropsychology and an athletic director emeritus at Drexel University in Philadelphia. “Some people may be ‘broken’ by a crisis, while others emerge from a stressful experience sometimes even stronger than before,” he says. An abundance of research backs this up. Rather than cower in the face of competition or opposition, Williams just keeps showing up with power, strength, and skill, adds James Rodriguez, PhD, LCSW, a clinical social worker and the director of trauma-informed services at the NYU McSilver Institute for Poverty Policy and Research in New York City. She continues to send the message: “Despite your best attempts, you will not defeat me,” he says. “The not-so-secret ingredient is mental toughness, or resilience, which enables people to actually grow through adversity,” Dr. Zillmer explains. While mental toughness is talked about often in sports, it translates to everyday life as well. “Mental toughness and resilience can be learned,” Zillmer says. They’re skills and qualities that are accessible to everyone. Ultimately, it’s about treating yourself well, building both mental strength and mental flexibility, and cultivating a sense of purpose and belonging in the world. Williams has made her mark on the world of sports, and inspired so many, not just because of the serves she’s hit or games she’s won. It’s her attitude, grace, and resilience on and off the court that make her an icon of mental toughness, according to Zillmer. Here are six examples of that quality.

1. She Has Unapologetically Set Boundaries Between Her Work and Personal Life

“Mental fitness for me is just really learning to shut down,” she told Selena Gomez in an Instagram Live chat in August. “I have serious boundaries, and I don’t let anyone cross those boundaries.” According to Zillmer, this kind of separation between a high-stakes professional sports career and personal life can help build resilience and prevent or lessen the impact of burnout. These firm boundaries likely contributed to the fact that Williams played at an elite level into her forties, which is extremely rare in tennis, he says. “Certainly, her athletic life was very much goal-oriented and ultra-structured,” Zillmer says. Separating this from her personal life may have allowed her to be less goal oriented and more playful in her personal life, he says. Finding this type of balance can ultimately allow people to push themselves to a very high intensity, he adds, because they’re also giving themselves adequate recovery time. Even those of us with lower-stakes careers could benefit from a strong separation between work and personal life.

2. She Has Spoken Out About Disparities in Maternal Health — and Shared Her Own Story

In an essay published in April 2022 in Elle, Williams wrote about the four surgeries she had in the days after giving birth to her daughter in 2017, all due to various complications. She revealed that she had to advocate loudly and repeatedly for the life-saving tests and procedures that the medical staff initially didn’t want to run. “In the U.S., Black women are nearly three times more likely to die during or after childbirth than their white counterparts,” Williams wrote, adding that many of these deaths are considered preventable. “Being heard and appropriately treated was the difference between life or death for me.” Williams’s ability to advocate for herself, even in an unfamiliar situation, is certainly an example of her resilience, and something we can all aim to emulate, Zillmer says. “Mental toughness includes taking control of a situation or your life, being able to handle things at once, and being influential rather than being controlled by a competitor, or in this case, medical bureaucracy.”

3. She Finds Joy in a Highly Competitive Sport — and Isn’t Afraid to Show It

It’s no secret that tennis is an especially high-pressure sport. Players compete alone, travel often, and are subject to constant scrutiny by the press and the sport itself. Williams embraces that pressure. “This sport has given me so much,” she wrote in her Vogue essay. “I love to win. I love the battle. I love to entertain. I’m not sure every player sees it that way, but I love the performance aspect of it — to be able to entertain people week after week.” Williams’s appreciation for all aspects of her sport, not just winning, is key to her success. “Sports by definition is competitive, hard, stressful, and deals with a constantly changing environment,” Zillmer says. Learning to enjoy all the ups, downs, and pressures of the job, at least to some degree, is the very definition of resilience and mental toughness.

4. She Finds Motivation in Setbacks

Serena Williams wasn’t always an ace. “When I was little, I was not very good at tennis. I was so sad when I didn’t get all the early opportunities that Venus got, but that helped me,” Williams wrote in Vogue, referencing her older sister Venus, who also went on to have a very successful professional career. “It made me work harder, turning me into a savage fighter.” She’s fought her way out of many scoreboard holes to win matches (including, famously, the 2012 U.S. Open championship match), and has been dubbed the “queen of comebacks” in headlines in the Guardian and the New York Times. “You can never count her out,” Chris Evert, a former world No. 1 tennis player, told Reuters about Williams in 2011. That kind of determination in the face of adversity is part of what defines mental toughness, Zillmer says, adding that sibling rivalry is a great way for people to learn resilience starting at a young age. Learning to cope with failure early on, and even be motivated by it, is another thing that sets certain individuals apart.

5. She Loses With Grace

Losing is part of all sports. And Williams has lost many tennis matches throughout her career. She does it with grace — even when she lost the (presumed) final match of her career. She stayed on court after that game and thanked her family, friends, and fans for their love and support. “Dealing with winning is easy, but losing is tough,” Zillmer says. If and when a loser does muster up that good sportsmanship, he or she actually has a lot more to gain by doing it graciously than sorely. “In sports psychology, losing graciously can also help someone maintain belief in themselves, even after (or because of) a setback.” It can help keep your confidence up, which makes you more likely to succeed in the future.

6. She Persevered Even in the Face of Sexism and Racism

As one of the few Black athletes in a very white sport, Williams has been the target of both overt and covert racism throughout her career. An article published in September 2016 in Vox reported numerous examples of how over her career, Williams has been likened to a gorilla, called manly, been hypersexualized, and endured racist slurs and death threats from a crowd at a 2001 tournament at Indian Wells — among other incidents. These examples show that Williams has had to endure a lot of challenges to become a professional athlete and compete, ones that others have not faced. “Serena Williams has not been afraid to call out racism, to talk about it clearly, and confront it in the media,” Dr. Rodriguez says. “In many ways, I think one of her contributions has been helping people understand the impact of that, and not sidestepping the conversation.” Top athletes need to have high levels of self-esteem, or at least confidence in their own skills and abilities, Rodriguez says. And though people have tried to undermine it, Williams has this. “Serena is someone who exudes confidence and comfort in her own skin,” he adds.