Mark Wahlberg plays a college professor with a near-suicidal addiction to gambling in his new film, “The Gambler.” While he knew moviegoers would have little trouble buying into him as a guy with an obsession for blackjack, the “day job” side of his character would be trickier. The Boston native, famed for his “blue collar types” on the screen, is “no viewer’s idea of a professorial type,” Justin Chang complained in Variety.

“You need to challenge yourself and surprise audiences,” Wahlberg says in his own defense. “People have me figured out? Mix it up on them. I jumped at this chance. That meant committing to being the most prepared I’ve probably ever been on a set. I had to, just to be believable. I mean, me as a college professor? I read with some professors, went to lectures, got a taste of how they hold a class.”

Jim Bennett, his character, teaches literature and quotes Shakespeare. He once published a novel, but now he’s lost, sure of only one thing - that he’s headed for mediocrity. Wahlberg knew he’d have to master screenwriter William “The Departed” Monahan’s dialogue to have a prayer of being convincing in the part.

Wahlberg, who only finished up his high school degree last year, insists that the real “stretch” for him in “The Gambler” is the actual gambling. Whatever you might guess about the muscular movie star, rolling the dice in Vegas with his “Entourage” is not his thing.

“I try to refrain,” he says. “I do. I try to make the only times I bet be when there’s a repeat of a fight on TV, and I can talk one of my friends into betting on the loser. I like sure things, knowing I’m gonna win.”

He waxes poetic on the subject.

“But I DO gamble on myself every day in my career. I make the wrong bet and lose, I have nobody to blame but myself.”

He gets why people gamble, “the thrill. You know, in the original version of ‘The Gambler’ (1974) Jimmy Caan’s character only feels alive in that instant, waiting for the dice to stop rolling, the roulette wheel to stop, for that last card to turn over.”

But there’s another way the addiction manifests itself. Jim Bennett “is trying to strip himself of everything positive in his life … He’s not the kind of guy who will do himself in. But he’s not bothered all that much about putting these loan sharks in a position to do some harm to him.”

Critics are collectively undecided about Wahlberg’s work in the film, though Todd McCarthy of The Hollywood Reporter says he “carries off the central role with what could be called determined elan.” And with awards buzz for the remake fading, Wahlberg is already focused on a couple of other William Monahan projects - “Mojave,” which he has filmed, and “American Desperadoes,” a period piece about the “Cocaine Cowboys” of Florida’s drug trade in the 1980s.

And then there’s the thing that has put Wahlberg in the headlines over the past month, his efforts to be pardoned for his criminal record, assault and other crimes he committed in Massachusetts in the 1980s when he was a teenager. He caught some flak for asking for the pardon, but got a break when his most prominent victim, a man named Johnny Trinh, came out in favor of the pardon. Wahlberg had allegedly blinded Trihn in an assault in 1988, but Trihn told the Washington Post Wahlberg “was not responsible for that…My left eye was already gone.”

Wahlberg takes a deep breath and sighs.

“What a weight lifted off my shoulders, to realize that I didn’t cause this horrible injury to him,” the actor, now 43, says. “I have carried that guilt for years and years and years. That is such an act of graciousness, him saying that.

“But look, I’ve lived my life ever since trying to better myself as a person, to do right, knowing that I’ve caused pain and grief. That’s what I will continue to do whether I receive a pardon or not. I teach my kids, it’s about giving back until you get a second chance. I got my diploma, just so I could show my kids that self-improvement never stops. You stick with it. So, pardon or not, I’m in a good place.”