The 44-year-old singer, who shares Brooklyn with wife Vanessa Lachey, was rehearsing the song for an upcoming gig — a performance that had his only daughter captivated.
“All I am, all I’ll be / Everything in this world, all that I’ll ever need is in your eyes, shining at me,” he sings, while Brooklyn’s smile beams bright the entire time. “I do cherish you. For the rest of my life, you don’t have to think twice / I will love you still.”
“Daddy’s Girl Forever!” Vanessa wrote in her post’s caption, adding a rainbow of heart emojis.
The recent heartwarming video might explain why Brooklyn was far less happy earlier this month, when she had to leave her dad to attend her first day of school.
Vanessa shared an honest photo of the moment, with Brooklyn looking adorably pouty as she sat on the family’s front stoop with her head down and her hands between her knees.
Posing next to a sign reading, “Brooklyn’s 1st day of 4 yr. old preschool” alongside the date, the little girl was ready for a day of learning regardless of her expression — wearing a cute bunny-pattern outfit, a red bow, gold Mary Janes and socks with a pencil-like design.
Brooklyn’s big brother Camden John, 6, was far more happy as he headed off on his first day of kindergarten. Sharing a series of snapshots presumably taken by Vanessa, Nick posed with his smiley oldest child while the latter wore a sports-themed backpack and a blue-and-khaki school uniform.
The second image showed the father-son pair sharing a sweet smooch, while the third featured a cringing Camden pushing his dad’s face away.
Like most great parents, regardless of the interests his kids take on and the direction life leads them in, Lachey just wants to support them in whatever they choose — and for them to be healthy and happy.
“They can do whatever they want with their life. I don’t have any expectations on what they become,” said the father of three (son Phoenix Robert turns 2 in December) in March 2017.
“As long as they’re good people and they’re happy and they’re healthy then I think, as a parent, that’s what you want for your kids,” he added.
This article originally appeared on PEOPLE.