“Guardians of the Galaxy” star Chris Pratt spoke at last Friday’s March of Dimes Celebration of Babies — and things got emotional as he recounted the birth of his son, Jack.

Chris arrives at the March of Dimes Celebration of Babies at the Regent Beverly Wilshire Hotel in Beverly Hills. (Photo: Newscom)

Chris arrives at the March of Dimes Celebration of Babies at the Regent Beverly Wilshire Hotel in Beverly Hills. (Photo: Newscom)

Jack, now 2, entered the world nine weeks before his due date weighing just 3 pounds, 12 ounces .

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“I made promises in that moment about what kind of dad I wanted to be, and I just prayed that he’d live long enough that I could keep them,” he said.

Baby Jack at the Farmers Market in Studio City, Calif. with his parents. (Photo: Newscom)

Baby Jack at the Farmers Market in Studio City, Calif. with his parents. (Photo: Newscom)

Chris, who graces the pages of GQ’s 2014 Men of the Year issue, told the magazine doctors told him they need to be prepared for a special-needs child. Although they were devastated, Chris said, “It also felt like, you know, ‘We can do this. He’s alive.'”

Chris at GQ's Annual Men of the Year Party in Hollywood. (Photo: John Salangsang/Newscom)

Chris at GQ’s Annual Men of the Year Party in Hollywood. (Photo: John Salangsang/Newscom)

Jack’s birth “redefined” Chris’s faith in God, he told PEOPLE in July:

“It restored my faith in God, not that it needed to be restored, but it really redefined it. The baby was so beautiful to us, and I look back at the photos of him and it must have been jarring for other people to come in and see him. But to us he was so beautiful and perfect.”

#tbt Happy Birthday Baby Jack! Love Mom??

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In his speech, Chris said his son is now a “strong, smart, happy, funny, beautiful boy” who loves monster trucks, Daniel Tiger and even vegetables.