In 2007, she finished fifth on season five of Nashville Star. Then, in 2011, she lasted 28 days on Survivor: South Pacific. Now, audiences will see her again on The Amazing Race, which kicks off season 25 Friday night.
And who is Duncan competing with? Keith Tollefson, a fellow Survivor contestant – who also happens to be her new husband.
Tollefson and Duncan, who wed this summer, met in Samoa while filming Survivor. Sparks flew and they soon became a couple.
They got engaged in February 2013 and were supposed to walk down the aisle this June – until they got the call to do The Amazing Race.
"The wedding was supposed to be on June 12 in the Caribbean," Duncan tells PEOPLE. "We had this big destination wedding planned, but then The Amazing Race came along. So we canceled everything and lost a lot of deposits."
Adds Tollefson, 28: "We didn't want to change the wedding, but how often do you get an opportunity like this? We had to do it. Also, I knew we could really compete. The areas where I'm weak, she's strong, and vice versa. And this was a chance to show that we weren't just a showmance; we're a real couple with a real relationship."
The couple won't tell PEOPLE how well they did on the Race, but there's one good sign that it didn't destroy their relationship: They got married after returning to the states.
"When we got back, I had no time to decompress," says Duncan, 30. "It was wedding detail hell – and I hated it! But it all turned out well and it was a wonderful day.
Duncan, a country singer who released a single, "Roll All Night," on Monday, admits that the Race wasn't easy.
"I'm really calm; I don't normally panic," she says. "But The Amazing Race brought out my panic mode. There were some really stressful moments – and I hate being stressed!"
Tollefson, who works as an energy advisor, agrees that racing around the world was rough.
"One mistake is enough to get you eliminated from the race," he says. "So I was always the one who was like, 'Whitney, read the clue again. Read it 100 times.' I became annoying because I was so meticulous."
"At least in Survivor, there was some down time," he adds. "On The Amazing Race, every second counts."
Not that either show is easy. "Oh, Survivor is much harder, all the way around," says Duncan. "But I feel blessed that we got to do both shows. It's really an honor."
The Amazing Race premieres on Friday at 8 p.m. ET on CBS.