The Oscar winner admits that took some convincing.
"I had to get to the point where I saw [getting married] as more than just the thing to do," McConaughey tells GQ for its November cover story. "I wanted to really want to. You know, I didn't want it to be a destination; the fun is that we're on the adventure together."
Ultimately, McConaughey, 44, indeed tied the knot with longtime girlfriend Camila Alves in 2012 – but says that took a lot of reflecting.
"We talked about it spiritually. We did a lot of reading and talked to a lot of people that had been divorced, a lot of people that had been happily married. We talked to our pastor," he says. "In the end, our understanding was, 'Let's go make a covenant, with you, me, and God.' "
Peggy Sirota / GQ
"Look, some of it had to do with her putting it on me," he admits. "It took her going, 'C'mon, Big Boy, Mr. Easygoing-We'll-Get-to-It-When-We-Get-to-It. Either s--- or get off the pot."
Post-wedding, the actor has been enjoying what's been dubbed a "McConaissance," although he admits balancing his roles – as husband, father of three, friend and respected actor – take work.
"I'm happy to say I feel like I'm in the black," says McConaughey, whose new movie, Interstellar, opens Nov. 5. "The one thing that's gone into the debit is me being a good friend. Career, marriage, fatherhood – the others are doing good."
To say his career is "doing good" might be an understatement, as he continues to bask in his Best Actor win at the Oscars for his role as rebellious HIV patient Ron Woodroof in Dallas Buyers Club.
McConaughey, the king of shirtless beach romps, says his obsession with his physique served him well as he shed 38 pounds for the role.
"I am vain," he admits. "I think vanity is a good thing. It's done more good things for me than it has not."
"I would have been embarrassed if I didn't get to where I needed to get," he says of his shocking weight loss. "That was vanity at work. Not 'Where did my muscles go?' "
He also brushes off people who claim he changed his body simply to prove he should be considered a "serious" actor.
"It wasn't some clever choice I made," he says. "It was a necessity for the role, a very clear decision: 'If I don't look like I'm gonna die, you don't believe I have HIV.' Period."