Tim McGraw Still 'Transfixed' by Wife Faith Hill After 18 Years of Marriage
updated 09/17/2014 AT 06:30 PM EDT
•originally published 09/17/2014 AT 04:00 PM EDT
While promoting his new album Sundown Heaven Town, Tim McGraw got a little assistance from wife Faith Hill, who was at his side Tuesday at sunrise for his performance on Good Morning America and after sundown for his American Express Unstaged show in New York City.
The couple, who will celebrate their 18th wedding anniversary next month, dueted on their hit "Meanwhile Back at Mama's," while the crowd sang along and cheered.
It's a song that McGraw chose to record after seeing his wife's emotional reaction to the demo.
"When it got to the end, where it said, 'Me and you back at mama's,' she started crying," McGraw recalled. "I said, 'I'm going to record it and you're going to record it with me.'"
It soon became the singer's 50th Top 10 on Billboard's Hot Country chart.
"We really haven't recorded that many songs together," said McGraw. "Just a handful. And we try to only record songs that we think are special to us. And this was one of those songs."
Hill is clearly her husband's biggest fan. But he's also hers: McGraw described how his wife's 1999 smash hit "Breathe" still impacts him. "It's a piece of art to me," he recently told PEOPLE. "Anytime I get to see my wife perform it, it just transfixes me."