Valerie Bertinelli on Mackenzie Phillips, Weight Loss, 'Terrific Dad' Eddie Van Halen

Oct. 14, 2009— -- Valerie Bertinelli attributes her newfound happiness learning to deal with her problems honestly, and she applauded former co-star Mackenzie Phillips for coming forward with her story of abuse.

"You're not tortured that long for nothing," Bertinelli told "Good Morning America" co-anchor Diane Sawyer today. "She was a very tortured soul. I'm seeing this light come out of her because she's letting go of a lot of that pain."

"It really kills me that people will not believe something coming out of her," she said. "I say give her grace."

Bertinelli let go of her own pain and found her own grace after losing more than 40 pounds on Jenny Craig and showing off her bikini body on the cover of People magazine. Part of that journey, she says, was learning to forgive herself.

"I'm still doing that everyday, daily…trying to forgive myself for who I believe I was," she said. "It's a daily struggle."

After sharing her personal strife and lessons in learning to overcome her addiction to food in the memoir "Losing It," Bertinelli is back with a new message and a new book: "Finding It."

This new book takes an intimate look at how she discovered how to live the best life possible at the age of 49. She offers advice on how to send yourself positive messages from "that little voice you hear in your head" to finding clarity in your life by cleaning out your closets.

"I do that often ... it helps," she said. "It takes away the chaos I think a little bit."

Bertinelli became America's sweetheart at the young age of 15 on "One Day At A Time," where she struggled with her own body image opposite co-star MacKenzie Phillips.

"If my jeans were two sizes bigger ... than Mackenzie's, I thought I was a fat hog," Bertinelli told "20/20" recently. "I just didn't think highly of myself. I always felt less-than."