Jennifer Garner Looked 'So Happy' on Set of New Film in Atlanta: Source

Jennifer Garner was spotted on the set of Simon vs. The Homo Sapiens Agenda, and a source told PEOPLE, "I have never seen her look so happy before"

Photo: AKM-GSI

Jennifer Garner gave a passionate speech in front of members of Congress on Thursday, advocating for early childhood education.

But on Monday, the mother of three and Golden Globe-winning actress was back to work — filming a role for a new movie in Atlanta, Georgia.

Garner, 44, was spotted on set of Simon vs. The Homo Sapiens Agenda — where a source told PEOPLE the actress was in great spirits.

“I have never seen her look so happy before,” the insider said.

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An adaptation of Becky Albertalli’s 2015 novel of the same name, the film tells the story of Simon (Jurassic World‘s Nick Robinson) — a 16-year-old closeted gay teenager who struggles to keep his sexuality hidden after a classmate discovers his secret and begins blackmailing him.

The Alias alum plays Simon’s mom in the coming-of-age story, directed by producer Greg Berlanti (Arrow, Flash, Supergirl). Katherine Langford, Alexandra Shipp, Logan Miller, Josh Duhamel and Tony Hale also star.

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On March 14, Garner’s estranged husband Ben Affleck revealed in a Facebook post that he had completed treatment for alcohol addiction.

In his statement, he thanked Garner — with whom he shares three kids: Violet, 11, Seraphina, 7, and Sam, 5.

“I want to live life to the fullest and be the best father I can be. I want my kids to know there is no shame in getting help when you need it,”Affleck, 44, wrote — adding, “I’m lucky to have the love of my family and friends, including my co-parent, Jen, who has supported me and cared for our kids as I’ve done the work I set out to do.”