Denis Leary confesses a nun changed his life after young 'troublemaker' days

Leary, 67, confessed he was just another rebellious teenager at a Catholic school until Sister Rosemary Sullivan showed faith in the now-famous actor. 

"I didn't believe in what they were teaching... this nun grabs me in the hallway and goes, 'Leary, you're in the musical,'" he recalled. "'I don't want to be in a musical,' but [she said] 'You have to,' so I go..."

After the divine intervention, Leary suddenly became interested in participating in the musical when he showed up at the rehearsal space that afternoon.

"It's all the hottest girls in high school," Leary quipped. 

During the auditions, Leary was confident he could sing since musical talents ran in his family. He was given a role in the play, and he told Hudson, "That moment changed my life."

"I told all the hockey players, 'You guys got to do this musical,'" he said.

Leary continued his rags-to-riches story, as he pointed out that his family were Irish immigrants and didn't have money to send him to college.

But with the help of Sister Sullivan, she didn't just get Leary onstage - she helped him with his next act. 

WATCH: DENIS LEARY PREPARED 'MY WHOLE LIFE' TO PLAY 'COMEDY VERSION' OF MILITARY FIGURE IN NEW SITCOM

When it came time for college, Sister Sullivan guided him toward an audition at Emerson College, which earned him a full scholarship. 

"She changed my life," Leary repeated wholeheartedly. "I stayed friends with her until she died."

"I would do an HBO special, it's just filthy," he admitted. "She'd call me up and go, 'I love the new special,' and I'm like, 'Sister, the language.'"

Sister Sullivan replied, "Ah, you kids were saying that stuff in high school."

More recently, Leary plays a colonel in his latest Hollywood project, "Going Dutch."

On the FOX comedy, Leary stars as U.S. Army Colonel Patrick Quinn, who is reassigned to a base in The Netherlands. He goes from combat command to a base staffed with misfits who he is tasked with bringing up to snuff, aided by his estranged daughter, played by Taylor Misiak, and right-hand officer, Executive Officer Major Abraham Shah, played by former "Community" star Danny Pudi.