In an open letter to her mother and newborn daughter shared on Reddit, Serena Williams wrote heartfelt words about body positivity, and how she overcame people saying her body is too masculine. 

"I've been called man because I appeared outwardly strong. It has been said that that I use drugs (No, I have always had far too much integrity to behave dishonestly in order to gain an advantage)," Williams wrote. "It has been said I don't belong in women's sports — that I belong in men's — because I look stronger than many other women do. (No, I just work hard and I was born with this badass body and proud of it)."

The tennis superstar also wrote that she is proud that her daughter, Alexis Olympia, shares a few of her mother's features, including her "strong, muscular, powerful, sensational arms and body."

In the letter, Williams thanked her mother for demonstrating that beautiful women come in all shapes and sizes.

"I am proud we were able to show them what some women look like. We don't all look the same. We are curvy, strong, muscular, tall, small, just to name a few, and all the same: we are women and proud!"

Now that she herself is a mother, Williams also wondered how her mother kept calm amidst members of the public calling her daughters harsh things. "Mom, I'm not sure how you did not go off on every single reporter, person, announcer and quite frankly, hater, who was too ignorant to understand the power of a black woman," she wrote.

And she said that she hopes to be able to do the same. "Thank you for being the role model I needed to endure all the hardships that I now regard as a challenges — ones that I enjoy. I hope to teach my baby Alexis Olympia the same, and have the same fortitude you have had."

You can read Williams' letter in full on Reddit.