The acclaimed actor opened up to ET about his new action-crime comedy and his powerhouse scene partner.
The pair recently spoke with ET's Kevin Frazier via video chat and the stars had nothing but praise for one another and the chance to share the screen.
"I gotta say, it was an extraordinary experience," Harrelson shared. "I've always loved Kevin, I think he is a living legend, you know, and in my mind, he’s one of the funniest human beings [even] before I met him."
According to Hart, 42, getting the opportunity to work scenes with Harrelson was simply "amazing."
"You're looking at an all-around good person, you know?" Hart shared. "He's happy, he's a happy guy, he's living his life correctly for him and getting the most absolute joy out of the way that he’s chosen to live it and I’m a fan of that."
"And you're talking about a guy that’s been in the business for over 30 years," Hart continued. "This guy's been doing this for a very long time and been doing it at a very high level, so [he has] my respect, my admiration. Anybody that’s done this this long and accomplished what he's accomplished, you definitely have to soak that up and be a sponge and a student at times."
For Harrelson, 60, acting alongside Hart was "difficult" because he couldn't keep his composure around the comedy superstar.
"I was laughing the whole time and I destroyed takes 'cause I was laughing," he shared. "And, you know, The Man From Toronto is not supposed to be laughing!"
In the film, a case of mistaken identity sees an ordinary man with a propensity for screwing up (Hart) getting mixed up with an international assassin known as The Man From Toronto (Harrelson), and violent hijinks ensue.
This means the film is absolutely filled with action sequence and stunts -- something Harrelson said was more fitting for Hart than for himself.
"I can say, for Kevin, it was no problem. For me, I’m not, you know, I’m not as coordinated as him. I’m not the athlete he is," Harrelson recalled. "So, in a sense, I had to do things over and over again."
That being said, Harrelson also wasn't chomping at the bit to get on Hart's level when it came to fitness and workout regimens.
"Kevin starts working out at 4:30 in the morning," Harrelson said. "That’s a conversation stopper for me."
Fans can check out all the comedy and explosive action when The Man From Toronto launches globally on Netflix on June 24.