Actress Valerie Bertinelli was 15 when she landed the sitcom role that would make her a household name. But, in the years since "One Day At a Time," she has had her ups and downs, most famously on the bathroom scale. Fans watched as she struggled with "Losing It," as she called her first memoir.

Now, Bertinelli is, as a new memoir testifies, "Finding It" -- her own voice, a new perspective on her body, motherhood and her broken marriage to rocker Eddie Van Halen.

"I've been given an opportunity to be, I guess, the poster child for getting your s*** together, maybe?" Bertinelli said, chuckling.

No wonder that she recently appeared on "Oprah" to support her "One Day at a Time" costar, Mackenzie Phillips, as Phillips revealed that she'd had a incestuous relationship with her father, singer John Phillips.

Bertinelli said she had no idea any such relationship existed. Ironically, she'd spent her teenage days on the set jealous of Mackenzie Phillip's sex appeal, on and off camera.

"She was much more [gutsy] than I was," Bertinelli said. "She knew how to get in there first, I was too shy. ... I was 16. Your life revolves around yourself. And if my jeans were two sizes bigger ... than Mackenzie's, I thought I was a fat hog. ... I just didn't think highly of myself. I always felt less-than."

Those lifelong feelings of anxiety and insecurity don't go away easily, even after losing all the weight and feeling the love from her fans. Her new book, "Finding It," shows Bertinelli, 49, dealing with a host of new life challenges, and facing up to the far less-fabulous side of being slim: "maintenance," or keeping the weight off.

"I'm still in it," she said. "There's no past tense with maintenance. It's an everyday occurrence. There's no, like, 'Ta-da' moment during maintenance. It's all like, 'Oh, ta-da, I had another good day.'"

It's a task that is notoriously challenging for Bertinelli, as it was, for example, for her former Jenny Craig cohort, Kirstie Alley.

"I've never kept it off this long," said Bertinelli, who once weighed upwards of 170 pounds. "It's a challenge in a totally different way because I know about losing weight, done it before. Been there, done that, bought a million T-shirts, all different sizes, but maintaining it, that's what I'm going through right now."

Marital Strife Weighed on Bertinelli

Bertinelli was 20 in 1981 when she wed one of rock's greatest guitarists, Eddie Van Halen.

"I love his smile and his eyes and his hands, and, mentally, I love his honesty," she told "Good Morning America" in a 1985 interview.

In 1991, the couple's son, Wolfgang, was born; named, they said, after classical composer Wolfgang Amadeus Mozart.

"I was lying in my hospital room, watching the 11 o'clock news after giving birth to Wolfie and they were making fun of my son's name that night," Bertinelli said. "I'm like, are you kidding me? I just gave birth."

In an "Arsenio Hall Show" appearance in 1994 and elsewhere, the couple publicly delighted in Wolfgang's high-spiritedness. But the marriage was damaged by mutual infidelities and Van Halen's personal demons. Their strife had Bertinelli worried for their son.

"I didn't want Wolfie to see this is what two people who love each other, this is how they behave," Bertinelli said. "I didn't want him growing up and marrying someone like me who was going to treat him like, you know, crap. Because that's basically what it got down to, I was treating Ed terribly. I had an opinion about his lifestyle that I didn't approve of and, so, I was going to treat him like that."

Their many disagreements finally overwhelmed Bertinelli's longtime determination to stay together.

"And they just added up, added up, added up to where it just became unbearable for both of us," she said.

Since their 2005 split, they've rebuilt a cordial relationship. But, then, two years later, Bertinelli got some stunning news.

Wolfgang, then 16, was to be Van Halen's new bassist and go on tour as a member of one of rock 'n' roll's most notorious party bands.

"We just, like, started playing one summer and I just sort of slipped in," the teen said at a news conference to announce the new tour.

Bertinelli said it brought her worst fears to the surface.

"That was about it," Bertinelli said, laughing. "You're going to take my sweet innocent boy and take him on the road? Yeah, that's my own personal hell.

"I wasn't concerned at all that he was going to be having sex on the road. ... My son is a virgin. I don't know what you think but my son is a virgin, as far as I'm concerned.

"I have to make sure he's not watching TV on Friday night. Oh, God."

Bertinelli realized that she'd never given motherly counsel to Wolfgang on intimate relationships.

"Wolfie, I think maybe we should have a talk about some of this stuff," she remembered telling him. "And he's like, 'Why, you're my mom, eww.'

"And, then, when, you know, he said, 'You know what, I'll just talk to dad about it,' I was, 'OK, cool,' ... and then I went, 'Oh, crap, he's going to talk to dad about it.'"

Tips on love and sex from a rock star? A fretful Bertinelli and her boyfriend, Tom Vitale, pressed their ears to his dressing room door as Eddie Van Halen gave their son some fatherly advice.

"We hear Ed go, 'When you give your heart away, just be careful. You got to be careful of all the skanks and whores that are going to want to go out with you because you're in a rock 'n' roll band and your last name's Van Halen,'" Bertinelli said, chuckling. "It's like, oh, OK, but I like the skanks and whore part because that, that rings true, too."

After the tour, Wolfgang, who's now 18, returned to high school. He remains two credits shy of graduation, however. It's a sore point for his mother, an avid reader who's still mad at herself for never getting her own diploma.

"I just feel you should have your diploma," Bertinelli said. "It makes me feel stupid. I know I'm not stupid, but I feel stupid because I don't have that degree."

As Bertinelli pondered getting a general equivalency diploma, a Jennie Craig executive proposed a new goal: How about a bikini?

"I thought, 'I need something else to keep me motivated to stay on this path,'" Bertinelli said of why she was motivated the pass the bikini test.

That meant months of workouts and running with trainer Christopher Lane. But it got Bertinelli to 122 pounds.

"I haven't been in one of these in 30 years," she said of her bikini. "All I know is that I worked my butt off to get in that suit."

A Little Airbrushing for Bertinelli

Of the picture, she said, "I liked the look in my face. Because the look on my face was pure, 'I can't believe I did this either.'"

Bertinelli admits that the famous cover image of her sleek silhouette was photoshopped ... but only a body part most might not have anticipated.

"I'm like, yeah, they airbrushed right here, because it was cold," she said, pointing to her breasts. "Because you're not supposed to have nipples on a national magazine."

And, now, with Lane's help, Bertinelli is doing an exercise video. It's easy to note her workout attitude on-camera is not so gung-ho.

"Do you really want to know how I feel?" she says during one taped workout. "I am happy we are done."

Fun for Bertinelli means time in the kitchen with her beau of five years, businessman Vitale, who has also dropped 35 pounds. She's confident that her life is on the right path, and will stay that way.

And she promised not to carry around 170 pounds again.

"No, never," she said. "Too many people besides myself are depending on me. So I am not going to do that, because I think I would disappoint too many people. I want people to be inspired by me. And I am inspired by them."