On Tuesday, former "Good Morning America" host Joan Lunden revealed on "GMA" that she has been diagnosed with breast cancer, CNN reports.

Fellow "GMA" host and breast cancer survivor, Robin Roberts was also on set during Lunden's shocking announcement.

Lunden revealed to Roberts, "I heard those words that every woman fears and never wants to hear: 'You have breast cancer.'"

Lunden then went on to say that the breast cancer originally was not found in her annual mammogram. It was her follow-up ultrasound that revealed the cancer.

She explained that finding out about her breast cancer through the follow-up was completely devastating given that her original tests revealed that she was fine.

"Nothing showed in my mammogram and you come out of there like, 'Yes, one more year. I'm okay,'" said Lunden. "And then you go all happy-go-lucky into the ultrasound and she kept going back to one spot."

Luden's recently diagnosed breast cancer has been described as an "an 'aggressive' kind of cancer that will require her to undergo chemotherapy, surgery and radiation, though she is expected to make a full recovery," ABC News reports.

Lunden is already starting her chemotherapy treatment.

Though Lunden's breast cancer discovery was initially devastating news for Lunden and her family, she later revealed that being diagnosed with breast cancer is now empowering her to speak out and inspire others who are dealing with the disease.

"It completely changed my entire frame of how I was looking at it," Lunden said on "GMA." "I went from being a victim to being empowered and having a purpose."

She explained that her father, who has passed away, was the inspiration behind her wanting to speak out about her diagnosis.

"The other night I was going to bed and I said, 'You know, if he [my father] was looking down right now, he would say, 'All right, you know you've got this and you've lived your life in front of an audience. Use it. Learn everything you can. Impart that information. Go out and try to inspire and maybe save lives. You don't have to be a doctor with a scalpel to maybe change that.'"

Lunden co-hosted "Good Morning America" from 1980 to 1997.