The EGOT winner — who’s featured on PEOPLE’s 50th anniversary cover with 10 other superstars — opens up about the song “that changed everything”

John Legend will always feel “grateful” for his career-changing song “All of Me.”

The love ballad, which was inspired by his relationship with Chrissy Teigen has become a go-to wedding song for couples around the world — and the EGOT winner, 45, says he’s always happy to perform the track.

“You never know what’s going to happen with songs. I had a feeling it was going to be successful. I told my label, ‘Keep working on it,’” he recalls in PEOPLE’s special edition 50th anniversary issue (on stands April 12). “This is going to be my biggest song if we do it right. It took a long time … It came out in August of 2013 and didn’t hit No. 1 on the charts until, I think, May of 2014.”

John Legend.

While some singers may tire of singing their most-popular hits, “I’m grateful that this song has had this much impact and that people want to hear it, and that people want to sing along with it at my shows,” says Legend. “I’ll never get tired of singing it.”

Chrissy Teigen and John Legend in his “All of Me” music video.

The music video also has special meaning to Legend, who shot it in Italy with Teigen, 38, days before their fairytale wedding at Lake Como.

“Nabil Elderkin, the same guy who directed the video where we met, he was the director of this video as well,” recalls Legend. “We went to Lake Como a little bit early and shot the video on the Thursday and Friday before we got married. We finished the shoot, we get ready for our rehearsal dinner, and then the next day we get married.”

Looking back at their journey together, Legend is proud of everything he and Teigen have built. “Chrissy and I have gone through so much together,” says Legend, who’s dad to daughters Luna, 7, Esti, 15 months, and sons Miles, 5, and Wren, 9 months.

“There’s been so many highs, some lows, but we’ve been together through it all,” he adds. “She’s my best friend, she’s my partner, my lover. She’s everythign that I could want in a wife.”