ET caught up with McConaughey atop the Empire State Building, where Camila also surprised him with some great news.
They say behind every successful man stands a stronger and wiser woman. Matthew McConaughey and Camila Alves-McConaughey personified that old adage the day he embarked on a three-week, lone-man trip to a remote town of Texas to write his memoir, Greenlights.
The Academy Award winner conjured up that memory while accepting the honor to light up the Empire State Building green to celebrate the author nearing 100 weeks on the New York Times Best Seller list, and only ET was there when Camila surprised her hubby with the exciting news.
In true McConaughey fashion, the 53-year-old let out a big whoop and hugged his wife to celebrate the achievement. And while at the podium thanking his team for helping his 2020 memoir reach incredible heights, McConaughey recalled the final moments before he said goodbye to Camila and the kids.
As McConaughey tells it, he was on his way out packing up the final things on the back of his pickup truck, the main essentials -- steaks, water, tequila and his journals comprised of about a million words, give or take.
"I remember the last words she said -- I had just loaded the back of my truck to go off to Marshall, Texas with all my journals, probably a million words," McConaughey recalled. "I was kind of intimidated and I was thinking I gotta go through the structure."
The trip would be daunting, as he was heading to Marshall, Texas, about five hours northeast of Austin, Texas.
"I loaded up the back of my truck with a bunch of steaks, water and tequila and headed out for three weeks to go to a place with no electricity, nothing but my journals," he continued. "[Camila] could tell I was nervous. And as I left she goes, "Hey babe, stop.' She goes, 'One rule: there are no rules.'"
Armed with confidence thanks to a supportive wife, McConaughey says those words "opened up my floodgates to go out and go write."
Greenlights would become a monumental success thanks to some astonishing tales that left fans with their jaws on the floor. For instance, McConaughey wrote about his father, James Donald, once telling him about how he wanted to die. James Donald died in 1992.
"He's always told me and my brothers,'" the actor wrote in his book. "'Boys, when I go, I'm gonna be making love to your mother.' And that's what happened. He had a heart attack when he climaxed."
Speaking to ET's Rachel Smith, McConaughey described the best part about his book having a lasting impact.
"I have people come up and say I read your book it meant a lot to me and they make sure to grab me and say, 'I’m serious that book did this for me and that for me and helped me do something I was afraid of,'" he says. "I hear those things and that reciprocation of putting out art helping people in a positive constructive way. That’s the best affirmation I could get. More than extremely cool."
McConaughey -- who with Camila shares 15-year-old son, Levi, 13-year-old daughter, Vida, and 10-year-old son, Livingston -- now has a new book out, Just Because, a picture book in which the Failure to Launch star tackles contradictions.
"Because I hear my children feeling pressured to be absolute," he explains. "I hear other kids who feel they have to be absolute. We need a sense of identity with one true thing. The truth of world and living is not that it’s a contradiction. We can have contradictions ourselves. My truth may not be yours. Now I know both sides and can make up my mind."
According to the book's description, McConaughey "has crafted a soulful and irreverent collection of life lessons that empowers readers, big and small, to celebrate how we are all full of possibility."
Just Because is out now.