Matt Damon describes to People what it's like to be a dad to 6 month old Isabella with wife Luciana. She is the first born for both Matt, 36. Luciana, 30, had another daughter Alexia, 8, from a previous marriage.

At a press event for his new movie The Good Shepherd, he said, "It's great, great. That's been just amazing. It defies description, actually. I don't really know how to talk about it because I don't really know – I feel like I got made a member of a club that I didn't know existed."

"I didn't think that this would happen to me," Damon said. "Other people were always showing me baby pictures or trying to hand me the baby, and I was like, 'Get that thing away from me. I don't want to touch your kid. Give me a break.' But I'm totally into it now."

At first, he said, "I was kind of excited for my daughter to be 2. I was excited for her to start talking and walking and toddling around hanging out, but I didn't realize how much personality little people have right off the bat. So it's just been fun."

He said his favorite activity with Isabella is making her laugh. "You do this thing where you can either give her (a raspberry) on the stomach or if you sort of act like you're going to munch her underarm, and she laughs like a little machine gun. And it's like I could do it forever."

Posted 4:40pm EST 12-11-06