Oksana Grigorieva: How I Dropped the Baby Weight

Oksana Grigorieva has already dropped her baby weight -- just about a month after welcoming Lucia with beau Mel Gibson.

When asked by "Extra's" Mario Lopez how she got slim, Grigorieva says, "I don't know. Just being an active mother, I guess. It just snapped right back in."

Check out adorable photos of celeb babies

How's Gibson as a father?

"He's a great dad," Grigorieva says. "He sings a lot to her."

Grigorieva spoke to "Extra" the same day her single "Angel" -- from her album "Beautiful Heartache" -- was released on iTunes.

She plans to donate the money from the downloads to a charity close to her heart, Chernobyl Children's Project International. Learn more about the charity here.