From PEOPLE Magazine Click to enlarge
The night before Valerie Bertinelli prepared to step out in public wearing a bikini—for the first time in nearly 30 years!—she found herself unable to sleep. As her mind raced with insecurity ("I thought, Am I really going to do this? Can I pull this off?" the actress admits), Bertinelli tried to summon up a pep talk, telling herself, "What am I so afraid of? Come on—it's just a bathing suit!"

And yet as any woman knows, those innocent-looking strips of Lycra can be a terrifying sight—especially for someone just shy of her 49th birthday (April 23), who only two years ago tipped the scales at 172 lbs.—more than 40 lbs. over her goal weight for her 5'4" frame. But after whittling herself down to 132 lbs. in about 9 months on Jenny Craig (for whom she serves as a company spokeswoman), Bertinelli, who had last worn a bikini when she was 20, was ready for a new challenge. "I thought, If I'm so afraid of a bikini, there's something wrong. And so I had to get back into one!"

And so—after about a year of exercising on her own while losing weight, primarily by walking 10,000 steps a day—she hired a personal trainer in December. Before long she was running up to five times a week and doing regular strength training (for details, see box). Finally, during what she calls the bikini "homestretch"—the last three weeks—she trimmed her daily caloric intake from 1,700 (which is how much she eats to maintain her weight loss) to around 1,200, and cut out salt and her regular "splurge" glass of champagne. "It was crunch time," she explains, "like getting ready for your class reunion!"

The result? Bertinell dropped another 9 lbs. to get down to 123. (She says she hopes to "settle in" at 125, and that she has drawn a "stake in the ground" at 132 lbs., meaning she hopes to never let herself get above that number again.) Even better, she is now in the best shape of her life. "I never, ever, ever had deltoids!" she says, breaking out into a laugh. "Oh my God, when I'm doing exercises and I see them pop out, I'm like, Yes!"

Even so, Bertinelli admits that, after a lifetime of being "consumed" by body issues (as a teen on the '70s sitcom One Day at a Time, she would go on crash diets), it remains a challenge for her to shake the "voices in my head" that say, "She's let herself go," Bertinelli says, adding that she often feels, "I'm just one jalapeño popper away from being 40 lbs. heavier again—that's what still resonates in my head." And when she looks at her body, "My eyes go immediately to the parts I don't like, the 'jiggly bits.'" (What are those, one might ask? She points to her upper thighs.)

Which is exactly why she wanted to bare her bikini body to the world. "I felt the fear—and I did it anyway!" she says. "Yes, I'm working on the mental part of adjusting to this body. But I deserve to have ripped arms! We all just need to appreciate our bodies for what they are, jiggly bits and all."

And so on the morning of the shoot for her latest Jenny Craig ad—which, yes, features her in a bikini and will be revealed during the April 1 Oprah show—Bertinelli got out of bed at 5:30 a.m. and told herself, "Here I go. Let's just do it," before squeezing in "a last-chance workout" at her Palm Springs, Calif., hotel gym.

When the moment finally arrived for her to reveal her bikini body—and her pierced belly button, which she had done in 1996—Bertinelli did so with the support of her longtime boyfriend, Tom Vitale, 47, an investment fund manager, who whistled appreciatively. "She has worked so hard," says Vitale, who himself has lost 31 lbs. on Jenny Craig (see sidebar), "and I am very, very proud of her." It was hard for Valerie not to feel proud too. Her body "is not one of those perfect bodies you see in Hollywood, where everyone is a double size 0," says the star, who is a comfortable size 6. "But I'm happy. I feel really good for my age." And although she knows she will "have to stay vigilant" to keep the weight from creeping back on, that's a challenge she is willing to face. "This," she says, "is just the beginning of the journey."