The smile on her face is so genuine, it wouldn’t require a second take to confirm that Michelle Borth is really (really) happy with her current job.

In the part of Catherine Rollins on "Hawaii Five-0," the actress has found the success she’s craved since arriving in Hollywood a decade ago. She’s had the role of Steve McGarrett’s girlfriend since the rebooted series premiered in 2010, but this season, the show’s third, Borth has become more than just a pretty face.

She’s done several butt-kicking action scenes, climbed over a high-rise hotel railing to get to the floor below — yes, that was Borth — and given McGarrett someone prettier than Danno to argue with.

"Five-0" has been a welcome change for Borth, who relocated to Hawaii for the show.

The 34-year-old actress has worked consistently on everything from "bad, bad low-budget independent films," she said, to the critically acclaimed but short-lived HBO series "Tell Me You Love Me."

Borth earned her success "the hard way," she said, and she’s proud of it. There were a lot of cattle-call auditions, one-liners on shows and single-episode guest appearances.

"I’ve been able to support myself acting for over a decade now, but nobody knows my name because I have been on shows that nobody watches and they get canceled after one season," Borth said recently while relaxing at The Modern Hotel in Waikiki. "I have been doing the grind for a while, and finally I was like, I want to be on a show that people know the name of. It has a cachet to it."

That might sound like a trivial measure of success, but consider Borth’s background.

She grew up in New Jersey and New York as the daughter of a single mother who struggled to make ends meet. Borth helped raise her two younger brothers, who still call her "Mammina," Borth said.

As a youth, the only constant in her life was gymnastics, and she longed to be Nadia Coma­neci, the Olympic gold medalist from Romania. She said the discipline required to excel in gymnastics meant missing friends’ birthday parties and sacrificing some of her femininity in favor of a rock-hard physique, she said.

"Gymnastics threw my whole body off," Borth said. "I kind of looked like a 12-year-old boy until my early 20s. It was really awkward. I had muscles where you shouldn’t have muscles."

That isn’t the case anymore. Borth’s look is striking: She’s Italian and Chilean, with dark eyes, long dark hair and a figure best described as petite.

The family moved around so often that Borth struggled to fit in at new schools, she said. Borth was the awkward girl who ate lunch by herself while reading Anne Rice books, the loner who didn’t go out of her way to make friends.

"I think a lot of that led to me becoming an actress because when you move around a lot and go to different schools, you have to learn to become somebody else all the time to fit in," Borth said. "So I learned how to be a chameleon really well. If not to fit in, to just hide."

Borth moved west after graduating from Pace University in Manhattan and took a variety of small parts before landing her breakthrough role in HBO’s "Tell Me You Love Me."

If there was any question whether she had left the loner behind, the 2007 show answered it. The series, which also starred Adam Scott ("Parks and Recreation"), Sonya Walger ("Lost") and Jane Alexander as a therapist, followed three couples with intimacy problems, and the on-screen simulated sex was controversial.

Still, it was easy explaining the role to her mother, a tough, free spirit with Sophia Loren beauty, Borth said. But the actress insisted her brothers not be allowed to watch the show.

Her mother was fine with that. Then she organized a block party so the neighbors could watch the premiere episode, the most graphic of the series.

"She was so proud," Borth said. "I just thought it was hysterical. I wasn’t there, but I can just imagine everyone with their mouths open and my mom going, ‘That’s my girl!’"

Borth credits her confidence to her mother. The actress isn’t a stereotype.

"I am not the girl next door," Borth said. "I would say I am a lot more complicated than that. I have a huge, huge heart, and I do everything to the extreme. I think I love to the extreme. I think I can be sad to the extreme. And I think I can be angry to the extreme."

Borth could have played a larger role on "Five-0" well before this season. Peter Lenkov, the show’s executive producer, had asked her several times, but Borth resisted because she was looking for her own series, she said.

Borth wound up as one of the stars on ABC’s "Combat Hospital," which told the story of doctors at a military hospital modeled after a real facility in Af­ghani­stan. It was canceled after a 13-episode run in the summer of 2011.

"I just needed to go out there and give it a shot," she said. "And I am glad I did because had I come on sooner, I think I would always be wondering what could have happened if I had tried."

As McGarrett’s girlfriend, Borth is the envy of legions of female fans of the show. She gets to spend all day on set with Alex O’Loughlin, the hunky Australian star who plays the top "Five-0" crime fighter.

But the work schedule is random. Some episodes include her in numerous scenes, and others require Borth on set for only two days. That leaves her with the rest of the week off and more time to surf, walk her dog or spend an entire day watching Netflix.

"Honestly, it’s a dream job," Borth said. "And I really adore Alex as a person and admire him so much. He has taught me a ton. He doesn’t really even know how grateful I am for him."

She admires O’Loughlin for his dedication to the show but also because he’s a family man, too.

"As a woman, I don’t know if I can have it all, if I can have kids and be married and handle the work," she said. "And I watch him every day and think if he can do it, I can do it."

The fans have been a large part of Borth’s life this season. More than any other "Five-0" cast member, she’s reached out with public appearances and a steady interaction on Twitter. It was a conscious decision because previous actresses with important roles — Taryn Manning, Larisa Oleynik and Lauren German — met with a negative reaction from fans that was inexplicable.

"At first I wanted to do it because in the past with previous female characters, they have had it really tough coming onto this show, especially with social media," Borth said. "And I knew that coming into this, and I knew that it wasn’t going to be everyone’s cup of tea. So my idea was to kind of reach out first and sort of send an olive branch out."

But the relationship grew. The communication became a conversation.

"They show me so much love here that I have never received on anything else I have worked on," Borth said. "It is really incredible the amount of support I have been given."

Her job doesn’t depend on this, and nothing the fans can say will dictate what happens on "Five-0." It’s just nice for Borth to be part of something.

"I want to embrace this fully, and I want to enjoy being a part of this show and I want the fans to enjoy that as well," she said. "And why not embrace all the love that people have to give?"