Ben Affleck "couldn't be happier" since the birth of his son.

The actor and his wife Jennifer Garner welcomed their third child, Samuel Garner Affleck, into the world last month. The proud parents already have two daughters six-year-old Violet and Seraphina, three and Ben is thrilled with the new arrival.

"He couldn't be happier. He loves his wife. He loves his family and he's proud he's legitimately proud you can just see it," a source close to Ben told People.

The 39-year-old Hollywood star has decided to relax his hectic work schedule in order to bond with Samuel. Ben loves spending time with his family and that is his primary focus for now.

"He's gets to spend a lot of time with his family and the idea that they have three kids right now is something that makes them both feel really good," the source added.

Shortly before giving birth, Jennifer admitted she feared it would be "so weird" to have another male around the house.

However, the 39-year-old actress is besotted with the baby and feels blessed to have three beautiful children.

"Jen is such a natural mother," explained the insider. "Jen is feeling good. She's so thrilled to have a little boy, and the girls already love him so much."

Ben and Jennifer have been married since 2005 and live in Brentwood, California.