The littlest member of Olivia Munn's family made the biggest difference in her battle with breast cancer.

The Newsroom alum opened up about how her 2-year-old son Malcolm, who she shares with John Mulaney, played an important role in her health journey. Re-posting a video of herself and the tiny tot playing by a kiddie pool in the backyard, Olivia wrote in an Instagram Story April 22, "This moment was last summer when I had already had three surgeries and recovery—mentally and physically—was pretty rough."