Charlize Theron Has Wanted to Adopt for a Long Time: Source

UPDATED 03/15/2012 at 10:00 AM EDT • Originally published 03/15/2012 at 08:00 AM EDT

Good things come to those who wait, as Charlize Theron has learned.

Following Wednesday's news that Theron has adopted a son, a source tells PEOPLE that the 2004 Oscar winner "has been trying to adopt a baby for a long time."

The Young Adult star, 36, "has been very patient and has a great attitude," the source says. "[She] is ecstatic about finally becoming a mom."

PHOTOS: Hollywood's Adoptive Families

Although Theron – who split from beau Staurt Townsend in 2010 after nine years together – is single, she won't be raising her new son Jackson alone.

"Charlize's mom [Gerda] has been helping out with the baby," the Theron insider says. "She seems so happy and will be a great mom."