Just over one month since Angelina Jolie announced to the world she had undergone a preventive double mastectomy, the actress and mother of six is back to "business as usual," according to her fiance, Brad Pitt.

"She's doing great," Pitt, 49, said today on " Good Morning America." "When she wrote her piece we had already come out the other end and we're feeling very good about it."

Angelina Jolie: 'Really Grateful for All the Support'

Jolie's essay in the New York Times explaining how she had both breasts removed after being diagnosed with a rare mutation of the BRCA gene that put her risk of developing breast cancer at nearly 90 percent sparked a global conversation on genetic screening and preemptive medical procedures.

Angelina Jolie Loses Aunt to Breast Cancer: Should You Get BRCA Gene Testing?

Pitt called the reaction to Jolie's decision to go public with her very private decision a "beautiful thing to watch."

"We were really surprised and moved [at] how many other people were dealing with the same issue," Pitt said. "Her idea was that someone could learn from her story and she would love to share that."

Brad Pitt Calls Angelina Jolie's Decision 'Heroic'

"I've been moved by it from every stage of this thing, especially now, and it seems to be a galvanizing moment for people dealing with this," he said. "She's certainly shown that if you do your research that you can make a decision that's the best for you. It doesn't have to be a scary thing. It can be an empowering thing."

Pitt was credited with standing by Jolie's side during her procedure and Jolie, 38, stood by her fiance's side at the June 2 world premiere of Pitt's new thriller, "World War Z," in London, her first public appearance since her op-ed.

"He's such a wonderful man and a wonderful father and I'm very, very lucky," she said at the premiere.

The couple and their six children have been traveling the world together for the release of "World War Z," celebrating Jolie's 38 th birthday one night early in Paris on June 3 and then celebrating again the next night in Berlin.

Pitt says the movie, in which he plays a United Nations troubleshooter trying to defend the world against a global zombie invasion, struck a chord for him as a dad in real-life.

"That's the only thing that keeps me up at night [as a dad]," he said. "Is everyone safe? We tried to make this thing as real as possible when we put in those fears, certainly."

While Pitt thinks about keeping his kids safe, they, specifically his sons, Knox, 4, Maddox, 11, and Pax, 8, inspired him to create the much-anticipated thriller, in theaters June 21.