Camila Sodi and Diego Luna
11/09/2008 AT 03:30 PM EST
For Diego Luna, becoming a dad has simplified his life.
"Well, it's just everything is easier now," the Mexican-born actor says of his 11-week-old baby boy, Jeronimo
, Saturday while promoting his new drama, Milk
, in Beverly Hills. "There is just one reason for you to be here. It's to make sure someone else is happy, and [he] has everything he needs. It's as simple as that."
Plus, Luna, 28, adds, Jeronimo is "the only guy who is not judging me now."
, Luna's character Jack Lira falls in love with Sean Penn's 1970s gay rights champion Harvey Milk. A performance his wife, Camila Sodi enjoyed, Luna tells PEOPLE.
"She laughed a lot about it," he says, adding that Camila has been spending time at home, "taking care of the baby."
"I'm here just talking about a film – it's just a film – everything now is just what it is," he says. "It can't be so important. Now, there's just one thing that really matters. It's a different kind of love that you didn't know existed. It makes everything easier really."