How ‘Reflection’ from ‘Mulan’ became Christina Aguilera’s big break

When Disney+ on Friday, viewers just might tear up when they hear a familiar ballad sung by a famous voice during the end credits: “Reflection” by Christina Aguilera.

Now 39, the pop star is once again taking on the tune that made her famous when she was little more than a 17-year-old former Disney Mouseketeer. Aguilera’s revamped rendition has garnered more than 6 million views since being posted Aug. 28 on YouTube.

Meanwhile, “Mulan” lyricist David Zippel remembers listening to the future star’s first demo of the moving track.

“When we heard her sing, it was like, ‘Oh my God. This kid sounds like she had the phrasing and understanding of lyrics of someone who had been singing for 25 years,’ ” Zippel told The Post. “Even then it was so palpable. She was a perfectionist even as a 17-year-old.”

Broadway’s Lea Salonga sings the number in the 1998 cartoon, but it’s Aguilera’s Disney-sanctioned single that has lived on, just as Celine Dion turned “Beauty and the Beast” into an easy-listening classic. The young Aguilera performed the hit on all the morning shows, which got her attention from the likes of Diane Warren. And after the success of “Reflection,” she signed with RCA and released the single “Genie in a Bottle” one year later in 1999.

Everything about the creation of “Reflection” was unlikely. For one, composer Alan Menken had been the sound of Disney since “The Little Mermaid,” writing the songs for “Beauty and the Beast,” “Aladdin” and “Hercules.”

For “Mulan,” Disney went in a different direction, pairing Zippel, who wrote lyrics for “Hercules” and the Broadway musical “City of Angels,” with a pop veteran — “Break My Stride” singer-songwriter Matthew Wilder, who also produced No Doubt’s album “Tragic Kingdom.”

“It was the best blind date I’d ever been on,” joked Zippel, who was lured in by a cassette tape of Wilder’s “Mulan” songs before meeting him. “We hit it off immediately and, of course, I think a huge part of why the song is so popular is because it’s beautiful and powerful and emotional. We’ve written other shows together since then. But we were put together randomly, and it worked.”

The songwriter has been surprised — and occasionally moved to tears — by the impact of his creation.

“It’s interesting because we wrote a song that was very specific to the situation,” said Zippel. “And yet there seems to be a universality about it, and I think that’s why it has endured.”

Some years later, the songwriter and his husband were throwing a soiree, and a friend brought visiting guests from out of the country, including a 16-year-old.

“And at some point in the middle of the party, the kid comes over to me and says, ‘Did you write “Reflection”?’ ” Zippel said. “And I said, ‘Yeah, I wrote the lyrics. My partner Matthew wrote the music.’ ”

The boy started to cry.

The emotional teen told Zippel that his tune had saved his life. He was gay, had been terrified to come out and considered killing himself.

“And then he heard that song,” an emotional Zippel remembered him saying. “And that song gave him the courage to tell his parents.

“It was like, wow. Sometimes things happen that have no relation to the creation of a work of art that are just kind of amazing,” he added. “I’m still touched even telling you this story.”