In Garth Brooks and Trisha Yearwood's eyes, the secret to a long-lasting marriage is fun. 

After all, the country music couple couldn't help but to joke around when sharing relationship advice to Good Morning America's Robin Roberts ahead of her wedding to longtime partner Amber Laign.

"We've been asked to tell you what we think the secret of a happy marriage is, because we've been at it for almost 18 years," Tisha gushed in a video message aired on Aug. 30. But after a few seconds of awkward silence, the 58-year-old turned to her husband and quipped, "Are you gonna go?"

The video cut to several hilarious outtakes of Garth, 61, and Trisha bickering and messing up their lines.

"One of you have to be f--king miserable," he joked in one scene, prompting Trisha to chime in, "That's right—and I am not happy."

Elsewhere in the clip, Garth offered up the age-old adage of "never go to bed mad at each other," though his wife didn't seem too thrilled with the basic tip. 

"What?" Trisha sarcastically retorted. "Did you Google that?"

So, what is the real key to a successful union? After Garth took Trisha by the hand, the two singers jointly said, "Marry your best friend!"

The sweet sentiment echoed words of wisdom the duo previously shared with E! News about marriage. For Trisha, who refers to herself as the "bonus mom" to Garth's three daughters Taylor, 31, August, 29, and Allie, 27, with ex Sandy Mahl, it all comes down to "friendship, laughter and mutual respect—and just love."

In fact, the "She's in Love with the Boy" singer noted that her husband was "flirting with me in text" as they got ready for the 2023 ACM Awards.

"You were flirting pretty hard," she lovingly teased Garth. "It's always a first date, you know? It just really is." 

To which he responded, "Come on, you can see why I'm in love with her."

Keep reading to see Trisha and Garth's cutest moments. 

While performing on stage during The Country Music Hall of Fame 2015 Medallion Ceremony, viewers couldn't help but see the pair's chemistry. 

Whenever there is a big country music celebration such as the 50th annual CMA Awards, these two are more than happy to support. 

While performing onstage at the 50th annual CMA Awards, the famous pair covered Loretta Lynn, Keith Whitley and other legends. 

The 50th Academy Of Country Music Awards at AT&T Stadium wouldn't be the same without this red carpet pair. 

When you do good, you feel good. Just look at Garth and Trisha at the ACM Lifting Lives Gala for proof. 

Back in September of 2015, the country music superstars were inducted into the Nashville Walk Of Fame. 

The 2016 Medallion Ceremony at the Country Music Hall of Fame and Museum was a happy affair for Garth and Trisha. 

In addition to receiving the Crystal Milestone Award at the 2008 Academy Of Country Music Awards, Garth also got to share the stage with his leading lady. 

You could say these two were the perfect match at the 48th annual CMA Awards.