Sunday had been hopeful last year she could beat her cancer because she already survived breast cancer in 2012 following multiple surgeries as well as chemotherapy and radiation.
Sunday's daughter Kennedy confirmed her mother's passing with a touching Instagram post shared by TMZ.
"To my unbelievably beautiful mama, thank you. Thank you for fighting as hard as you did for as long as you did. Thank you for being a best friend, a role model, a sister, and my mother all in one. Thank you for raising me to love Jesus, and show that love to others. That's something you did so well," Kennedy wrote.
"It breaks my heart to know you will never get to see me on my wedding day, or be there when I have my first kid. But I know you're watching over me. Although it hurts me so bad to watch you go, I'm so happy you are happy again."
Kennedy continued, "I'm happy you get to be with Jesus, and see your dad. I'm happy you aren't in pain anymore. I'm happy I got to have these past few months with you. I loved taking care of you. You'll always be my favorite patient. I love you to heaven and back a million times."
"I know one day we will meet again. Until then, I'll spend every minute missing you, and trying to make you proud. Rest easy mom, I'll see you soon," she concluded.
Sunday was declared cancer-free four years before her Survivor stint aired in 2016.
Sunday, a Christian who wrote Grit Girl: Power to Survive Inspired by Grace in 2018, gushed during her Survivor season, "There is nothing physically or emotionally that I can't do!"
At age 45, Sunday lasted in the game for 35 days and finished Millennials vs. Gen X in seventh place.
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Sunday was blindsided at Tribal Council with four votes after fellow castaway Jay Starrett played his hidden Immunity Idol because he thought he was in jeopardy.
(Jay only received one vote and David Wright earned himself two votes that evening).
Sunday expressed in her final words on Survivorhow her family would be proud of how she played.
"I slept in the dirt for 30 days, I did challenges I never would have done, I jumped off things I never would've jumped off of -- I'm honestly leaving so proud of myself and I have no regrets about it," Sunday said in her final words on the show.
But Sunday felt underestimated in the game ofSurvivor, as many of her fellow castaways dubbed her a goat.
"I felt like I came in with a certain skillset and that was my social game with my ability to connect with the Millennials, and I did both of those well," Sunday told Reality TV World in an exclusive December 2016 interview.
"I had good relationships with just about everybody, and I felt like I was able to go back and forth with votes, even with people who weren't necessarily in my alliance. So I felt like I was flexible."
Sunday added at the time, "I felt like I was likable enough where I could have [presented] a case to the jury."
Sunday also talked to Reality TV World about her casting experience and how surviving breast cancer might have heightened CBS and producers' interest in her.
"It was my second time applying. I applied for the first time with my son for Blood vs. Water, and then I applied again. I think that fact that I was a breast cancer survivor played a part in it," Sunday shared.
"And then later, not knowing what the theme was going to be, I think that fact I was a young adult pastor and worked with that [Millennials] age group is part of what got me on the show."
In addition, Sunday gushed about how she "had a blast" playing the Survivorand "would totally play again" if given the opportunity.