Growing up in Sugar Land, TX, Manuel always loved swimming, but at age 12, she almost gave up the sport for good because she was frustrated with the lack of diversity in the pool. "I was 12 years old, and for the first time in my young life, I had begun to realise I was different," Manuel wrote in a July 2018 letter to her younger self, published in The Undefeated. "I advanced quickly as a swimmer, so I was placed in training groups with kids much older than me. The more I excelled, though, the more I noticed a pattern developing in my interactions with others."
Despite the lack of people who looked like her in the sport and her feelings of isolation, Manuel decided to stick with it. "I've come home from practice many days and just cried about it with my parents and talked to them about it, talked to the ones that I love and feel their support, and then get back up the next day and go to practice and work hard because swimming is what I love to do," she told People during a July 2020 interview, adding, "I'm not going to let someone stand in my way."