While Robach was reluctant to get a breast exam in front of millions of viewers last month during the "GMA" October Pink initiative, little did she know how important it would be.
"That day, when I was asked to do something I really didn't want to do, something I had put off for more than a year, I had no way of knowing that I was in a life-or-death situation," she revealed in a blog post.
Weeks later, Robach thought she was going in for follow-up appointment, but it was then when doctors revealed her diagnosis.
Robach considered it virtually impossible for her to have cancer, writing, "I take care of myself and I have very little family history."
As for what's ahead, Robach will go into surgery on Thursday to get a bilateral mastectomy and reconstructive surgery.
"Only then will I know more about what that fight will fully entail, but I am mentally and physically as prepared as anyone can be in this situation," she wrote.
While the shocking news was seemingly hard to take at first, Robach is thankful she got checked and hopes her story inspires all woman to do the same.
"It is the difference between life and death," she wrote.