• Prince William recalled the night he joined Taylor Swift and Jon Bon Jovi on stage for a rendition of "Livin' on a Prayer"
  • The royal said Swift convinced him to go up the stage with her during the Centrepoint charity event at Kensington Palace in 2013
  • He said it made him realize that it's OK to have fun and "to not take yourself too seriously"

Prince William is opening up about the night he sang and danced onstage with Taylor Swift and what the experience taught him about not taking himself too seriously.

In a special Christmas episode of Apple Fitness+'s "Time to Walk" series, which premieres Monday, the Duke of Cambridge, 39, looked back at the time Swift led him to the stage to join Jon Bon Jovi for a rendition of "Livin' on a Prayer" during a Centrepoint charity event at Kensington Palace in 2013. 

The impromptu concert was described by Prince William's aides at the time as completely "off the cuff," according to People.

Revealing how the moment went down, Prince William recalled being nearly knocked off his feet after finding out that Swift and Bon Jovi were at the annual charity fundraising gala for Centrepoint, which the royal described as "a young homeless charity that I am very fond of and have supported for many years."

"When I sat down to watch Jon Bon Jovi do his performance, I thought, 'That's it. My job is done. I'll get dinner in a minute, and I might be able to have a chat [with] some people, and, you know, I'm off-duty a little bit now.' Little did I think what was going to happen next," Prince William was quoted by People as saying.

The prince, who is second in line to the British throne after his father Prince Charles, then shared that Swift, who was sitting on his left at the time, turned to him following Bon Jovi's first song and convinced him to go up the stage with her.

"She puts her hand on my arm, looks me in the eye, and says, 'Come on, William. Let's go and sing,'" he recalled.

The future king admitted that he still does "not know what came over" him at that moment and that he cringes each time he recalls what happened next.

"I don't understand why I gave in. But, frankly, if Taylor Swift looks you in the eye, touches your arm, and says, 'Come with me…' I got up like a puppy and went, 'Yeah, OK, that seems like a great idea. I'll follow you,'" Prince William added.

The royal said that he walked up on stage "in a trance" and that it was only when they were halfway through Bon Jovi's "Livin' On a Prayer" that he realized he was on stage performing a song he doesn't know the lyrics of.

But Prince William said he continued performing with the two musicians as the young boys and girls the charity had invited appeared to be enjoying the show, explaining, "I can't be the doofus who's going to ruin it for everyone."

The duke added that he "desperately" tried to remember the song's lyrics and sang as hard as he could. Throughout the song, however, he said he was "sweating" underneath his black tuxedo, likening himself to a swan who looked composed on the surface but was paddling its little legs fast under the water.

While Prince William has a lot of experience giving speeches on stage and being the center of attention during events with massive crowds, the royal said singing had taken him out of his comfort zone. But during such moments, he's learned to just "roll with it."

"There [are] so many pressures, but I think making a fool of yourself is OK. It's OK to not take yourself too seriously and have those moments where you let go and you just go, 'Do you know what? I'm OK with this,'" he shared. "So, yeah, go on and have a laugh. And don't go and watch the video of me singing. Or do go and watch it, but just laugh to yourself about how I was feeling."

Prince Willam teamed up with Apple Fitness+ earlier this year to record one of their audio walking experiences, which features personal stories from influential people to inspire users to walk more. He took part in the project as "Time to Walk" coincided with his efforts to promote better mental health and wellbeing.

Prince William's walk takes him through the Queen's Sandringham Estate in Norfolk, England — from Sandringham House, past St. Mary Magdalene Church and ending eventually in Anmer, where he and his wife Kate Middleton have a country home.

Three special audio airings of Prince William's "Time to Walk" episode will stream for free on Apple Music 1, the flagship global radio station on Apple Music, on Monday.

Prince William hopes the televised event will help propel the fight against climate change leading up to the COP26 summit in Scotland Prince William hopes the televised event will help propel the fight against climate change leading up to the COP26 summit in Scotland Photo: POOL / Ian Vogler