The very best day of Nick Lachey’s life happened 17 hours after his pregnant wife Vanessa started having contractions.

“The anticipation of having your first child and going into labor, it’s so tense," the VH1 host told Closer during the network's Save The Music Family Day. "There is so much going on.”

After 14 hours of labor and three hours of pushing, the couple’s little man Camden made his grand entrance on Sept. 12, 2012.

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Lachey with son Camden last month

Nick and Vanessa, who married just over a year earlier, were ecstatic about their growing family.

“You plan for it and think about it for so long and then this little life you’ve created is in your hands. It’s surreal,” gushes Nick. “The emotional waterfall that happened when I saw my son for the first time, I was just a mess.”

And Camden's birth instantly altered the former boy bander's life. “It makes everything you do and every decision you make not about you anymore," he marvels. "Once you have a kid, it's all about them, as it should be."

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Lachey and wife Vanessa on March 18

The 40-year-old has throughly enjoyed watching his 18-month-old son grow, admitting, "It’s a wild ride! You’re so tired but you’re not tired at all because you’ve got so much adrenaline pumping."

And he cherishes seeing Vanessa embrace her new role. “It’s fun to watch the woman you love evolve into motherhood.”