Amy Robach on Being 'Forever Bonded' with Robin Roberts Who Urged Her to Have Life-Saving Mammogram

Amy Robach is reflecting on her special relationship with Robin Roberts, eight years after the Good Morning America co-anchor convinced her to have her first mammogram. The 60-year-old urged her reluctant colleague to do it live on TV in October 2013, because she'd "save a life."

When Robach was diagnosed with breast cancer weeks later, the now-48-year-old knew that the life she helped save was her own.

"Robin and I instantly became sisters, because I think anyone who's walked down that path knows there's just a camaraderie that you can't explain," the GMA3: What You Need To Know and 20/20 co-anchor tells PEOPLE about their friendship.

"But it's more than that, though, because she and I both know how integral her role was in me getting that mammogram, which I completely credit with saving my life. We are forever bonded. We can speak without speaking," Robach shares.

"We can literally just look at each other across the set and know exactly what each other is thinking. There's a real trust there. There's a real bond there. There's a huge amount of respect and love that goes both ways between us," she continues.

When a GMA producer encouraged Robach to speak to Roberts about having the mammogram, it was six years after the latter co-anchor faced her own breast cancer diagnosis. Robach had a long list of reasons why she shouldn't have the examination live on TV.

"I really had no plans to actually get a mammogram," says the journalist, who was then a "perfectly healthy" 40-year-old. "I didn't think I should be the person. I really believe in authenticity, and I didn't want to just do something to say, 'Hey, everybody, do it,' when I actually had no intention of doing it."

"I knew the recommendation was that a woman could wait until she was 50, if she had no prior family history and I am not someone to run out and go get a test if I don't have to," Robach explains. "I wasn't interested, and I had zero family history."

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Roberts thought otherwise. "She looked at me and she said, 'You're exactly the person who should do it,'" Robach says. "She said, 'Because did you know, Amy, that more than 80 percent of breast cancer survivors, patients, have no family history? You're the one who thinks you don't need the test – and I hope you don't, and you probably don't. But, if you can convince one woman who doesn't think she needs…to have this mammogram…I promise you, you will save a life.' "

"When she said that to me, it was really hard to say no. I remember kind of having a visceral reaction. I had chills come over me. It felt like a watershed moment. I didn't really know why," she notes.

"I felt emotional when I was completely unemotional going in there," Robach adds. "I said, 'My gosh, you just completely changed my mind. Okay, I'll do it.' And I gave her hug. We think about that moment all the time, because that was the moment that she saved my life."

On Oct. 30, 29 days after having that mammogram live on television, Robach was back on the GMA sofa, sandwiched between Roberts and ABC Chief Medical Correspondent, Dr. Jennifer Ashton. Holding their hands, she tearfully revealed her breast cancer diagnosis to viewers.

There was a gap between the first mammogram and the final diagnosis, because Robach kept putting off getting a follow-up test after doctors saw "something suspicious" on her first result.

"Truthfully, I was irritated that I had to get a follow-up mammogram or that they told me I needed one," she says, adding, "and so, I put it off, because I had no fear of the outcome." Pushing off scheduling a mammogram is something that many women have done during the COVID-19 pandemic, after months of stay-at-home orders.

But Robach urges women not to procrastinate. "We're not talking about it as much because, obviously the No. 1 health focus in this country right now is combating COVID, but cancer is still happening," she says. "And sadly a lot of women and men are not getting the diagnoses they need to start the treatment they desperately need because they aren't getting those appointments."

"I just would urge everyone, if you have put it off to not hesitate. To pick up the phone to call your doctor and to make the appointment… And don't make the appointment once, make sure you make it every year, because it's not just a one and done thing. You have to follow up and make those annual [appointments] and make sure you're putting your health first," says Robach.

New two-hour episodes of 20/20 air Friday nights at 9:00 p.m. ET on ABC and stream on ABC News digital platforms and Hulu. You can also catch Amy on GMA3: What You Need to Know weekdays at 1:00 p.m. ET on ABC.