Robin Roberts on 'GMA' milestone anniversary: 'I'm not gonna be here another 20 years'

Thursday was a "Good Morning" for Robin Roberts, who celebrated 20 years on ABC's top-rated "Good Morning America."

Roberts, 61, said during the broadcast she was unaware of the milestone until she was tipped off by a producer. Roberts, a longtime ESPN reporter, began contributing to "GMA" in 1995 and moved to full-time news anchor in 2002. She was named co-anchor, alongside Charles Gibson and Diane Sawyer, in 2005.

The most-watched network morning program, which debuted in 1975, fêted its own with a studio decorated with Roberts cutouts and recorded messages. Tennis legend Billie Jean King remembered nudging Roberts away from ESPN when the "GMA" offer came in. Michelle Obama also had a message for her pal, whom Obama referred to as "my girl." The former first lady celebrated Roberts' "humor and grace, your curiosity and compassion. Oh, and your one-of-a-kind smile."

Robin Roberts has 'shed more tears' watching her partner fight cancer than she did during her own battles

"GMA" aired clips and caught up with some of the subjects of her reporting in a "Where Are They Now?" segment.

"That's what it about," Roberts said afterward, with tears in her eyes. "It's about the people we've met, hopefully the impact we've been able to have."

Patti LaBelle performed "New Attitude" in-studio, turning Roberts and some of her "GMA" colleagues – Lara Spencer, Michael Strahan and Ginger Zee – and Roberts' longtime partner, Amber Laign, into backup dancers.

Michael Strahan gushes over daughter Isabella's runway debut: 'Very proud of you'

Streaming shocker: 'Dancing With the Stars' moves from ABC to Disney+

"I can't believe it," Roberts tells USA TODAY, in disbelief of the milestone. "The places I've been, the people I've met; I am so blessed. I don't know any other way to say it. It has been such a thrill these last 20 years to be in peoples' lives and homes.

"I love it when ... we can share something with them and have real takeaway that could help them in their respective lives," she adds. "It will never grow old saying, 'Good Morning' to America. I love it."

In Roberts' new book, "Brighter by the Day: Waking Up to New Hopes and Dreams," out Tuesday, she reflects on her time at the show. The same day in 2012 that "GMA" became the top morning program, she also learned her myelodysplastic syndromes (MDS) diagnosis meant she might just have one or two 1-2 years to live without a successful bone marrow transplant. That year Roberts received healthy blood-forming cells from her sister, Sally-Ann Roberts.

20 must-read spring books from Viola Davis, Janelle Monáe, Robin Roberts, Don Winslow and more

Kim Kardashian tells Robin Roberts her comment on women in business was 'taken out of context'

Roberts also remembers in "Brighter by the Day" worrying that her emotional coverage of 2005's Hurricane Katrina might cost her that new anchor job. While on the ground for her report, she was unable to get in touch with her mother, Lucimarian Tolliver Roberts, another sister, Dorothy Roberts McEwen and two nieces, who rode out the storm in Biloxi, Mississippi. Shortly before going on air, she was able to get to her mother's house to see her family had weathered the hurricane just fine.

During her live report, Gibson asked about Roberts' family and she began to cry. She shed tears for those who lost loved ones, because her family was OK, and also, she writes, "I was having a WTF moment. 'What have I done? I thought. I just lost it on national television – with Charlie Gibson and Diane Sawyer! I'm out

"I did initially feel like, 'Oh my goodness. This is it. I'm gonna lose my job,'" remembers Roberts in an interview. "And it was ugly crying. It wasn't a cute cry. It was an ugly cry, but it really taught me something, the response that was so positive... It taught me to be more empathetic. And the way people responded after that really taught me just be you."

Nearly 17 years later, Roberts is not certain how much longer she'll occupy her anchor's seat.

"I'm not gonna be here another 20 years," she says. "I don't think anybody wants to see me at 80 years old saying, 'Good Morning America.' I'm going to want to move on to another chapter."

"This has been a terrific season in my life," she adds, "and I have no timetable on how much longer the season will last at 'Good Morning America,' but I'm going to treasure every single moment, and I'm going to try and make everybody's day a little bit brighter while I'm here."

'The prognosis is good': Robin Roberts reveals partner Amber Laign's breast cancer diagnosis:

Hollywood is ignoring tween girls. ‘Turning Red’ shows why that needs to change.

This article originally appeared on USA TODAY: 'GMA' anchor Robin Roberts on 20-year anniversary: 'I am so blessed'