Matthew McConaughey and Jimmy Fallon Sing Actor's First Children's Book “Just Because” — Watch

The actor chatted to 'Tonight Show' host Jimmy Fallon about his 'New York Times' Best Seller on the show

Matthew McConaughey can add singing to his string of many talents!

On Monday night, the actor joined Jimmy Fallon for a duet as the pair sang the words to his new children’s book and New York Times Best Seller Just Because on The Tonight Show Starring Jimmy Fallon, following the talk show’s return.

“I love that it has a rhythm to it,” Fallon told McConaughey, 53, as they first sat down to discuss the book, which was released on Sept. 12. “So what I was thinking would be kind of fun is if we added maybe a little music to it.”

“Oooh, I like that!” McConaughey agreed.

Fallon, 49, then recited lines from the actor’s book from his seat as the show's band accompanied him — and McConaughey followed after.

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Related: Matthew McConaughey's Kids Throw Him Surprise Party After His Book Becomes Bestseller

The host eventually handed his guest a microphone and they both walked over to the band and continued to take turns in singing more lines from the book as the audience clapped.

For the last couple of lines, the pair sang together, “Just because the sun is set, doesn’t mean it will not rise ... "

“Why?” Fallon — who is also a children's book author himself — asked as McConaughey playfully added, “Why’s that?”

The actor then stepped closer to the camera as he delivered his last line, “Because every day is a new gift, each one a new surprise!”, while the audience cheered.

Earlier on the show, McConaughey spoke about his kids’ reaction to his first children’s book. (The actor shares Levi, 15, Vida, 13, and Livingston, 10, with wife Camila Alves McConaughey.)

“The kids dig it!” he shared. “My daughter’s very visual; she loves the illustrations. My eldest and I have talked about similar scenarios that he’s going through in his teenage years. My youngest is still holding out to tell me if he likes it or not — but that’s kind of just his character.”

Related: Matthew McConaughey Says His First Children’s Book 'Just Because' Came to Him as a 'Ditty in a Dream'

Last month, the actor revealed in an exclusive chat with PEOPLE how the concept for his book Just Because was initiated.

“It came to me at 2:30 a.m. as a ditty in a dream," the Oscar winner shared. "It was a song in my mind, and I got up and wrote it down."

A spirited collection of life lessons and conundrums untangled in rhythmic couplets, the picture book sparked "a lot of good conversations" with his kids, he said.

The book also provides life lessons for older generations, McConaughey added: "My mom’s 91 and she said, 'That’s not just for kids. You even reminded me of some things in there.' "

Just Because, which follows McConaughey's bestselling 2020 memoir Greenlights, is available now wherever books are sold.

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