Following a live mammogram on "Good Morning America" to kick of Breast Cancer Awareness Month, Robach, then 40, received a phone call several weeks later, on Oct. 30, telling her she had stage 2 invasive breast cancer.
"It can make me emotional literally thinking about it right now," Robach said of that phone call. "When I first got diagnosed, it's just a whirlwind of so many decisions ... and it all happens so quickly."
Very soon after her diagnosis, Robach underwent a double mastectomy, followed by eight rounds of chemotherapy and then breast reconstruction surgery.
She also began to take a daily medication, tamoxifen, that she will continue to take for three more years. The drug, which helps lower the risk of cancer recurrence, can induce symptoms of menopause, like hot flashes, night sweats and menstrual changes, according to the American Cancer Society.
Robach described the treatments she underwent as grueling, and the process of fighting cancer as a long and dark tunnel, one that included mental and physical changes including short-term memory loss and the loss of her hair.
What surprised Robach even more in her cancer journey was what happened once she finished treatment and was declared a cancer survivor.
"You think you're going to celebrate," said Robach. "But you're so sick still. You're so weak still. All of those chemicals are still in your body."
Cancer never leaves you.
Robach said she struggled emotionally and physically as she adjusted from fighting breast cancer to surviving it, noting, "Cancer never leaves you."
"Once you're finished with the treatments and the surgeries, there's a fear that steps in," she said. "You don't even have time to really think about it when you're fighting. When you stop actually fighting with treatments, you then think, 'Oh no, what's next? What happens now?'"
Those are questions likely asked by millions of people who have battled breast cancer, the second-most common cancer among women in the United States, according to the Centers for Disease Control and Prevention.
But while people and organizations rally around those undergoing breast cancer treatment, it can still be taboo to talk about breast cancer in general, and the struggles that survivors of breast cancer can face in the weeks, months and years after treatment.
"I've had so many conversations where if I mention cancer or talk about being a breast cancer survivor, or thriver, people immediately get uncomfortable," said Robach. "It's something that nobody necessarily wants to talk about it, and some people feel really uncomfortable knowing what to say next about it."
Following treatment, Robach and other breast cancer survivors face bodies that can be dramatically different than pre-cancer.
Looking at your body, and not recognizing it is a really frightening thing.
"When you're fighting for your life, it sounds silly to think about vanity, but it is a part of the cancer journey," said Robach, who experienced hair loss, changes in her skin tone and scars and the loss of her breasts from her double mastectomy. "Looking at your body, and not recognizing it is a really frightening thing, actually, because it happens so suddenly, and even with reconstruction, things are not the same, they never will be."
Physically, after finishing chemotherapy, Robach said it took at least one year for her to rebuild her strength, noting that in the aftermath of treatment, "You just feel weak, and you feel scared and you are dealing with all of the aftermath of chemo for months and months and months."
Mentally, it would take another year for her to feel like she could regain control of her life.
I was scared to even plan for a future.
"I would say it took me a full two years before I felt like, 'OK, how am I going to live my life? What am I going to do with my life?'" she said. "The truth is, I was scared to even plan for a future, to even plan for the next year or five years or 10 years. I felt like it was maybe jinxing my health, jinxing my remission."
Robach said what has helped her navigate the unknowns of her breast cancer journey has been finding someone she can talk about it with honestly, someone who has walked the same path before.
In Robach's case, that person has been "Good Morning America" co-anchor Robin Roberts, also a breast cancer survivor, whom Robach called a "beacon of light."
"I remember when I finished treatment, she told me this, 'Be careful. We all want to celebrate the end of chemo. We all want to celebrate the end of surgery, but you should prepare yourself for the next phase of cancer,'" Robach recalled. "When you're in remission, sure you're grateful, yes, you're excited, but there's a fear. ... You always have the threat of recurrence."
Cancer is something that you live with for the rest of your life.
Like many breast cancer survivors, Robach gets blood work done twice each year to check if any cancer has returned in her body, a reminder, she says, that cancer is "something that you live with for the rest of your life."
"I have a tough time, every time," she said, noting the days leading up to the test can be filled with "depression" and "fear."
But the biannual tests have also, in more recent years, become what Robach calls her "biannual reminder to live, and to live out loud."
In Robach's case, that has meant climbing mountains, traveling the globe, running marathons, feeling gratitude every day and fighting to become the healthiest version of herself in the years since her diagnosis.
"It makes me feel so joyful to know that I am challenging myself physically, and believing in my body again, trusting in my body, again, investing in my body again, and really doing everything in my power to make sure that if this thing comes back, or even if it's living in me now, I am in fight mode," said Robach. "At 48 years old, I'm significantly more healthy than I was in my 20s and 30s."
Cancer gave me a reason to be the best version of myself.
"Cancer gave me a reason to be the best version of myself, and that's what I've done," she said. "You realize that fear can either cripple you or it can motivate you, and it had been crippling me. And I decided to change it, and let that fear be motivating."
Robach said that after not wanting to do the mammogram on-air eight years ago because she did not want people talking about her breasts, she is now incredibly proud and grateful that she shared her breast cancer battle publicly.
I find talking about it makes it a little bit less painful.
"I would just encourage everyone to tell your story because it does save lives, it does impact lives and it frees you," she said. "I find talking about it makes it a little bit less painful because you're releasing it and you can have a shared experience with someone else because there are so many of us out there who've been through it. We're all brothers and sisters in this fight."
GoodMorningAmerica.com is tackling a different taboo women's health topic each month, breaking down stigmas on everything from mental health to infertility, STDs, orgasms and alcoholism.