When Melanie St. Fleur started medical school in Florida two years ago, she quickly proved her aptitude for the field, passing exams and succeeding in her courses while her peers struggled, she said.

But even so, there was one refrain she couldn’t get out of her mind: “I was like, ‘I don’t know how I got here,’ ” said St. Fleur, 29. “I felt like I was getting through by luck, basically … I just felt out of place from the very beginning.”

While doubts about her abilities were all in her head, feeling out of place wasn’t: St. Fleur, a Black woman, is surrounded by mostly White peers, she said — a reality that compounds her self-inflicted pressures by making her more conscious of how her peers view her, she said.

So when St. Fleur saw tennis star Naomi Osaka’s tweet on Sunday — about how she’s combating impostor syndrome with more positive affirmations — “it made me feel not alone,” St. Fleur said. “Like, ‘Okay, I’m not crazy, this happens — even to one of the best tennis players of our time.’”

In the tweet, Osaka, who plays in her first U.S. Open match as the tournament’s defending champion on Monday night, shared that “internally I think I’m never good enough. I’ve never told myself that I’ve done a good job but I do know I constantly tell myself that I suck or I could do better … Every time a new opportunity arises my first thought is, ‘wow, why me?’ ”

To cope, Osaka said she’s “gonna try to celebrate myself and my accomplishments more,” adding that “I think we all should. … Your life is your own and you shouldn’t value yourself on other people’s standards.” Part of those celebrations will include praising small wins, Osaka wrote, like recognizing when she wakes up and doesn’t procrastinate.

This isn’t the first time Osaka has been honest about mental health: In May, she withdrew from the French Open to prioritize her mental well-being after being hit with a $15,000 fine for opting out of required news conferences, which she said caused her anxiety. In doing so, Osaka — who is Japanese and Haitian — joined other women of color Olympic athletes in sharing their mental and emotional battles, including gymnast Simone Biles and sprinter Sha’Carri Richardson.

Osaka’s openness about her struggles with impostor syndrome — and her commitment to combating it by celebrating herself — resonated with many women, who praised her on social media for her honesty.

Lisa Yambra, a 35-year-old Realtor based in Houston, has dealt with impostor syndrome “pretty much my entire life,” she said.

For Yambra, that has historically manifested as being unable to bask in the glow of her accomplishments: “I’ve had many successes in life that I can never celebrate because I always feel like they weren’t good enough or I could’ve done more,” she said.

When Yambra graduated college with the distinction of magna cum laude, she said she thought, “I could’ve got summa [cum laude] if I tried harder.” More recently, when she received a second place award celebrating her sales from her brokerage firm, all she could think was, “I could’ve sold more, I could’ve done more,” she added.

This is a common manifestation of impostor syndrome, according to Kensa Gunter, an Atlanta-based clinical and sports psychologist: “It can interfere with our ability to celebrate our successes … the mind-set associated with impostor syndrome has us thinking about what more we could do, or what we could do next.”

This can be especially true for women of color, who may feel they have to overcome both sexism and racism to prove themselves. LaToya Fryer, a 38-year-old Black woman, grew up hearing that she had to “be twice as good as someone who doesn’t look like you to do the same thing,” she said.

Now, Fryer — a physical therapist in Tampa — faces that double standard on a daily basis. When she introduces herself to new patients as “Dr. Fryer,” White patients often respond by asking her where she went to school, she said. It’s only after she answers “Duke” that she feels their tone shift, she said — and even then, Fryer said, sometimes they respond by asking, “Which Duke?”

Recently, she added, one patient responded to her explanation of her educational attainments by saying, “Well, I’ll still be calling you LaToya.”

Moments like that prompt her to ponder: “Am I good enough? Did they just pass me through school? Did they just happen to give me a degree?”

That kind of doubt characterizes impostor syndrome, which often manifests as “this fear of being exposed as a fraud,” according to Lisa Or​​b​​é-Austin, a psychologist and executive coach in New York City and the co-author of “Own Your Greatness: Overcome Impostor Syndrome, Beat Self-Doubt, and Succeed in Life.”

Oftentimes, people respond to impostor syndrome through overwork or self-sabotage “in order to cover up this fear of being revealed,” Or​​b​​é-Austin added.

Research on impostor syndrome is limited, in part because it’s not formally recognized as a diagnosis, according to Or​​b​​é-Austin. But systemic racism and sexism often act as the infrastructure of it, which points to the limits of tackling it individually, Or​​b​​é-Austin said. Even so, she added, it’s important to remember “you have individual agency to make a difference [in your mental health] even if that system is trying to oppress you.”

Part of how people can do that is think about where their impostor system stems from — and often, that’s childhood and family dynamics, according to Or​​b​​é-Austin.

For St. Fleur, the medical student, and Yambra, the Realtor, their struggles stemmed from being bullied when they were young. And for Fryer, the physical therapist, it was a White parent questioning her placement in a childhood gifted and talented program that made her second-guess herself for the first time, she said.

Understanding the origin stories of where individual impostor syndrome comes from is crucial to tackling it, Or​​b​​é-Austin said: “Your current triggers are often related to why you developed impostor syndrome in the first place. … Once you understand your triggers and know what’s triggering you, you can disrupt the cycle. You can choose healthier behaviors.”

Part of how people can do that is by questioning negative thoughts rather than believing them, according to Or​​b​​é-Austin: “Our job is to examine [our thoughts], look for evidence, and if we don’t have evidence, countering the thoughts proactively.”

If people want to work with a therapist to tackle their impostor syndrome, they should “ask them if they know about impostor syndrome — do they have certain philosophies about how to work with it?” Or​​b​​é-Austin recommended.

And, as Osaka said, it’s also crucial to “define wins and successes for ourselves,” according to Gunter, the Atlanta-based psychologist. “I think it’s important to be able to acknowledge all of the progress and wins … not just the major moments.”

St. Fleur is trying to do just that, by celebrating making it to her third year of medical school. After just having taken her board exam and awaiting the results, she’s also practicing positivity: “Being in limbo is nerve-racking, but all I could do is wait and stay positive.”