Credit: Jonathan Leibson/

Giuliana Rancic has become the poster child for optimism.

The 37-year-old E! News co-host -- who was diagnosed with breast cancer in August -- will undergo a double mastectomy and immediate reconstruction next week, she announced on The Today Show Monday.

"Overall, she's in unbelievably great spirits," a source close to Rancic tells Us Weekly. "She's been working a lot. It keeps her motivated."

Giuliana's husband, Bill, 40, has been "very supportive" of her decision, the source adds. "They want to go into 2012 with a clean slate and put this all behind them."

Indeed, Giuliana is hoping for a "full recovery by New Year's Eve," she said on The Today Show. "We're planning to be in Times Square!"

Bill's love and support means the world to Giuliana, according to the Style Network star.

"Bill told me, 'I don't care about the physical results,'" she said. "I just want you around for another 50 years. I need you healthy. I need you as my wife. I need you as a mother to our kids.'"