When he landed a role in Steven Spielberg’s World War II epic Saving Private Ryan, Vin Diesel’s career went from the slow lane to the fast track. He quickly took parts in Boiler Room, Pitch Black and the animated Iron Giant before Rob Cohen’s action-packed 2001 film The Fast and the Furious made him a household name.

Now, nearly four years after his smoldering portrayal of Furious’ resident street racer Dominic Toretto and a string of action-hero roles in films like XXX and The Chronicles of Riddick, Diesel – who’s known for his tight abs, shaved head and gravely voice – is making a brave jump into the world of family friendly films with his role as Navy S.E.A.L Shane Wolfe in the upcoming Disney comedy The Pacifier.

In the film, out March 4, Diesel’s character is assigned to protect the children of an assassinated scientist who was working on a top-secret project before he was killed. While protecting his charges from ninjas, hirsute wrestling coaches and incorrigible Boy Scouts, Diesel’s Wolfe begins to learn a thing or two about himself while he slowly bonds with the seemingly bratty kids.

While The Pacifier wasn’t the obvious choice for Diesel – after all, only a few action stars have successfully been able to make the cinematic crossover into family fare – the comedic aspects of the film aren’t lost on the actor.

“I’ll tell you, [switching to comedy] was a source of anxiety for me initially because it was an all-out comedy,” says Diesel about his dive into previously uncharted waters. “It’s one thing to say, ‘It’s a comedy, so come in and you’ll laugh a little bit. But no promises.’ It’s another thing to say, ‘You’re gonna laugh so hard.’

“When some people say [that] comedies are so difficult to do, they don’t mean the actual production,” he continues. “Shooting a comedy isn’t physically demanding. It isn’t a complicated process while you’re doing it. What is difficult about a comedy is making sure that the jokes pay off – seeing the film at the end of the process and having the comedy [sequences] work.”

In some action-to-comedy crossovers, certain actors go to extremes in order to play against type – they dress in drag or make fun of their pre-determined personas. According to Diesel, his role in The Pacifier didn’t require him to go to any Mrs. Doubtfire-type extremes.

“It wasn’t like (snaps fingers), ‘I’m going to make fun of myself,’” he says. “I would’ve felt weird had it not had any action, though it was a comedy. It was always built into the script perfectly [and] that’s what made it work. It starts by having this built-in play on people’s perceptions [of me] portraying this role – and then you throw kids into it.”

Diesel’s Pacifier co-stars include teenagers Zoë (Brittany Snow) and Seth (Max Thierot), as well as an 8-year-old, a toddler and an infant. According to Diesel, working with these kids brought out emotions he never knew he possessed.

“The infants were twins, the toddlers were twins, and I would go away from the set or I’d be at home from the set over the weekend [and] I’d be thinking about those babies,” Diesel admits. “I’ve never had a relationship with a co-star so profound. It definitely pumped up that paternal instinct.”

As it turns out, Diesel connected with the child actors on more than just a purely paternal level. He’s been working the boards himself for as long as he’s been able to stand on them.

“I was an actor for as long as I can remember,” says Diesel of his days in the business before catapulting to action-film stardom in the late 1990s.

He’s also a product of his environment: According to Diesel, his dad, who taught theater at Brooklyn College in NYC, once directed a pre-Apocalypse Now Laurence Fishburne.

Diesel also has a directing credit under his belt, helming a short film called Multi-Facial which actually caught Spielberg’s eye once upon a time and led the director to cast Diesel in Saving Private Ryan. But it’s not Spielberg’s lengthy career that truly inspires Diesel.

“The career I’ve watched [the most] is Mel Gibson’s … and we all know why – it’s pretty damn obvious,” he says with a laugh. “The guy’s been able to create what he feels the need to create and that’s the key!”