Charlize Theron became overwhelmed with emotion when she recalled the moment she realized AIDS could be beaten in Africa.

During a panel discussion at the Mashable Social Good Summit, the U.N. Messenger of Peace recounted when she overheard a gay teenager inquiring about using a condom. It was at that moment she realized taboos had been overcome and fear had instead been replaced with positive action against the deadly disease, according to Huffpost Impact.

Theron noted that she realized the stigma surrounding AIDS had began to subside eight years ago, while she helped out as a volunteer at a workshop. After a volunteer had demonstrated a female condom to the class, a 16-year-old boy asked if he could use it for anal sex.

Charlize Theron shares moment that made her believe we can end AIDS http://t.co/XV6erJeLSt pic.twitter.com/3nMplZYh5m

— Huffington Post (@HuffingtonPost) September 29, 2015

“I was so moved because that never happened when I was growing up,” Theron said. “People didn’t feel safe to talk in that manner. I know that that boy is alive, because he felt safe enough in that environment to ask a question.”

“That’s when I knew we were starting something that was going to turn the needle,” she added.

And there has been progress. Since 2000, the number of new HIV cases has dropped by 35 percent, from 3.1 million to 2 million, according to UNAIDS.

But to wipe out the disease,Theron and other activists say that the world needs to lend more resources to grassroots groups.

“The people who are doing the good work are the small, grassroots organizations who are on the ground that nobody is talking about, nobody is supporting,” Theron said. “It’s the people living in the villages with those young girls, with those adolescents who are at high risk.”

Thank you @FLOTUS @CharlizeAfrica @glamourmag @PlanGlobal for raising your voices. #FundEducation #GlamourForEdu pic.twitter.com/ahaMDLh8g7

— Julia Gillard (@JuliaGillardGPE) September 29, 2015

While Theron is excited by the progress being made in Africa, she still worries about how the world may still be too “complacent” about the virus that is still the leading killer among adolescents in Africa and the second leading cause of death among all adolescents globally.

Charlize Theron says she hopes that by keeping the conversation going, she’ll be able to keep the momentum going, especially amongst women.

“That should be something we should all be concerned about,” Theron said of how AIDS disproportionately affects women. “That affects me. That affects you. That’s not just an African problem. That’s not just as Asia problem … that’s all of us.”