Reese Witherspoon is opening up about how her experience preparing for her role in the 2014 film Wild changed her trajectory as an actress completely. The drama, which was adapted from Cheryl Strayed’s Wild: From Lost to Found on the Pacific Crest Trail, and primarily featured Witherspoon as Cheryl hiking alone on the Pacific Crest Trail.

In a new profile for Interview magazine, the actress talks to Tracee Ellis Ross about preparing for the role, revealing that it changed her the most of every role she’s played.

“I was so scared to do that,” the 45-year-old Oscar-winning actress admits. “I had hypnosis, I was so scared. I was having panic attacks for three weeks before I started.”

As for why she felt so strongly, there were many elements to the film that left Witherspoon feeling so nervous to take on the part.

“There was the nudity, sexuality, and drug-use aspect, but also being alone on camera with no other actors,” she told Ross. “I hadn’t ever been alone in scenes for days and days. There were probably 25 days of the shoot where I had no other actor opposite me. It was just me and a camera and a backpack. I was like, ‘Is this going to be so boring?’”

In the end, the film was extremely successful, with both Witherspoon and her costar, Laura Dern, earning Oscar nominations for their respective roles.

Elsewhere in the interview, Reese answers Tracee’s question: “What is the most important thing to you about who you’ve become?” She goes on to specify, “I don’t mean careerwise, but as a person.”

“I now know what I’m good at, and I know what I’m not good at,” Witherspoon says. “My passions have become more intensified as I’ve gotten older. I truly believe that like-minded people who get together and push toward a greater good can create real change in this world. I only believe that because of the friendships I’ve made with extraordinary women like you over the past, I’d say, four years.”

She continued, “Before that, I felt so lonely, and it was really hard for me because a lot of the conversations I was having in rooms in Hollywood, well, I felt like I was the only one having them. When we all started getting together and meeting, I realized that women were having the same conversations across town in a different boardroom or on a different set, and it was enormously comforting to know that I wasn’t pushing a rock up a hill.”

“It’s still a lot of effort, but it felt more effortless with you guys involved,” she concluded. “And since then, the support that’s been created by this group of women feels like I have a chorus behind me.”