The 38-year-old actress shared her story during a podcast interview, as reported by Us Weekly, and went into detail regarding what took place.
"In season 3, I had a bad experience on set with being basically cornered into doing a scene partially naked, and I felt I had no choice in the matter," she said. "I was mortified and I was trembling, and when it was finished, I was crying my eyes out and I had to go on [to] do a very formidable, very strong scene thereafter."
Around a year later, however, Lilly says she ended up in a very similar situation all over again.
"In season 4, another scene came up where Kate was undressing, and I fought very hard to have that scene be under my control and I failed to control it again," she explained. "And so I then said, 'That's it, no more. You can write whatever you want — I won't do it again. I will never take my clothes off on this show again.' And I didn't."
Lilly went on to say that she believes she would handle those situations differently now that she is older and wiser.
"I've been doing this for nearly 15 years, so I kind of know the ropes," the Ant-Man and the Wasp actress said. "I'm a little bit better equipped now to not have uncomfortable experiences come up."
Lilly later said that she passes altogether on roles that call for nudity. "It's not because I think there's anything wrong with nudity," she clarified. "It's because I don't trust that I can be comfortable and safe."
"I'm lucky. I'm in a position — a very privileged position — where I'm allowed to be picky," Lilly added. "I can be picky. I've got enough success under my belt that I can be, and I feel for women who are just struggling to come up in the industry and don't really know how to navigate that."
While these past scenarios left a negative impact, Lilly also plenty of positive memories from her time on Lost. Specifially, she recalled how much she loved working with Michael Emerson (Benjamin Linus) and Terry O'Quinn (John Locke).
"Their immovability in a scene taught me about not bending to make my costars comfortable, which I think is a quintessentially female trait, to always try to accommodate and take care of whoever you're with," Lilly stated. "But they were never selfish, unkind or egotistical. They were just very strong and talented."
Lilly can currently be seen the aforementioned Ant-Man and the Wasp, which is playing in theaters now.