Brie Larson's SAG Award win solidifies her spot as Oscar favorite

NEW YORK (WABC) -- Another weekend and another win for the star of "Room," who picked up an award from the Screen Actors Guild to solidify her place as the odd-on Oscar favorite.

And if it seems like an overnight success story for Brie Larson, well, it was actually 15 years in the making.

"I'm so grateful to have had so much life, so many trials and tribulations," she said.

This period of her life began with Mark Wahlberg as "The Gambler," where she played his student. But it was as a mom confined to one "Room" that proved the breakout role.

Her son was born in captivity, his biological father their captor.

"I took eight months just to work on ma," she said. "I didn't take any other jobs, I just focused on creating her."

The actress lost weight and stayed indoors to get the complexion of a shut-in just right.

"I'm from California, so lack of sunlight, you really feel a difference," she said. "You feel rather sad, and spending so much time thinking and talking about sexual trauma was another thing that started to weigh heavy on me."

Despite all that, Larson said creating a character is a lot more comfortable for her than all of the limelight.

"Putting on heels, wearing make-up, talking about this movie, like continuing to be a social person when I really like to retreat and be inside is a really new experience," she said. "But so valuable. It's so valuable for the shy kid to try something new."