11/11/2013 at 02:05 PM EST
When Good Morning America
correspondent Amy Robach participated in an on-air mammogram screening last month as part of the show's October Pink Initiative to help encourage viewers to get checked, she had no idea how important that scan would be.
"I was a little reluctant at first," the journalist told colleague Robin Roberts
Monday morning, speaking out for the first time since the diagnosis. "I'm 40, I'm the age and I've been putting it off."
After the initial on-air mammogram, doctors followed up with additional tests and last week they made the shocking discovery that Robach has breast cancer.
The news came as a shock to Robach, who says she has no family history of the disease. "It's still hard for me to say the words out loud. I have breast cancer."
Married to former Melrose Place
star Andrew Shue
, Robach has two daughters and three stepsons. "Telling my children was the toughest part," Robach, who was joined by Shue and other cast members on the couch while making the announcement, said. "But that's when you get strong, because you have to be strong for other people."
Robach says while she doesn't know the stage of her cancer or if it has spread, "I have decided to have a bilateral mastectomy."
"You're going to beat this," her colleagues said, as Roberts held Robach's hand.
"I'm so grateful that I got the mammogram that day. Robin's words still echo inside of me 'If I got the mammogram on-air and saved one life then it's all worth it' she had said. It never occurred to me that that life would be mine," Robach said.