The most surprising thing about motherhood? "That I'm learning so much about myself through her," Frye, 30, told PEOPLE Saturday at the Chrysalis Butterfly Ball, a benefit for the homeless in Brentwood, Calif.
"Every day I look in her eyes, and I realize that she's teaching me. I thought I'd be able to pass on so many lessons, but I think it's mutual in that we're teaching each other, and she teaches me about love and life every day. I have to remind myself, she's a baby! Because she seems so much bigger than life."
Frye and Goldberg, 36, a producer of MTV's Punk'd, met in 1996 when Frye pitched him a film script while she was studying film at New York City's New School University. They tied the knot in Los Angeles in 1998.
Since giving birth to Poet, Frye says she's been staying in shape by "constantly running after her! And we do dance parties in the bedroom, so a lot of our exercises are about putting on Elmo and dancing to Elmo's World [on Sesame Street]."
As a former child star who survived early fame with her sanity intact, what would she do if Poet wanted to be an actress? "I don't know if I'll have a choice," she said, "but whatever she wants to do, I'm going to try and support. If she's anything like I was, my god."
Reporting by SCOTT HUVER