Annette Bening is reflecting on the life-changing experience of playing marathon swimmer Diana Nyad in the Netflix film Nyad.

At a screening this week in Los Angeles, Bening took part in a panel discussion about the film that focuses on Nyad’s real-life efforts in her 60s to become the first individual to swim from Cuba to Florida without a shark cage.

The performer, a four-time Oscar nominee, explained that she grew up in San Diego and is trained as a scuba diver.

But while she has always felt comfortable in the water, she had never been a serious swimmer.

To prepare for the film, she worked with former Olympian Rada Owen for roughly a year, in addition to hitting the gym with a personal trainer, and her nerves about the role — not to mention having to constantly be seen wearing a swimsuit — eventually faded.

“Now, if I don’t swim, I have to, I don’t know, grit my teeth,” she continued. “It is so deeply, deeply good for the brain and the soul, and I just love the water. I mean, I always have loved the water. It changed my life, for sure. I loved the training, and then when we were shooting, I loved being in the water.”

Nyad enthusiastically shared her support for Bening’s performance and pointed out that the actress rarely used stunt doubles. “She swam some days [for] eight hours a day,” said Nyad. “We professional swimmers watched her in the footage and said, ‘You can’t tell that that isn’t a professional swimmer.’ You did it, girlfriend.”

After premiere at this year’s Telluride Film Festival, Nyad opened in select theaters last month and is currently streaming on Netflix.

The film is considered Oscar contender for the performances of Bening and Foster.