The reality competition series is celebrating 20 years on television with a special reunion concert and they're inviting several previous winners, including Ruben Studdard, who won the competition in 2003, and Jordin Sparks, who won in 2007.
The two alums reflected on the biggest lessons they learned from being on Idol.
"The work ethic," said Studdard. "I will say they instilled to always be on time and be ready for curve balls. There's always something new happening."
"I agree," said Sparks.
"After this, it was a cake walk," she said. "If you can make it through this, you can make it through anything! There's a lot of fun moments, but it's a lot of hard work and sleepless night. You've got to believe in yourself to do it."
The winner from 2018, Maddie Poppe, shared the best piece of advice she received on the show, and it came from "American Idol" judge Katy Perry.
"Don't let anybody change you," said Poppe. "It might sound simple but truly going with my gut and sticking to my guns has helped me make a lot of important decisions in my career."
The celebration also features Scotty McCreery, David Cook, Lauren Alaina, Kris Allen and many more.