Leona Lewis is one of the greatest successes to come out of The X Factor franchise. She won the show in 2006 after being mentored by Simon Cowell and became a top-selling artist immediately with her cover of "A Moment Like This." This was the start of a musical partnership that lasted 8 years and came to a shocking end in 2014. https:\/\/www.youtube.com\/watch?vusPtd-2lzwg Leona Lewis Was 'Extremely Depressed' Under Syco Contract Leona was signed to Simon's label Syco Music after winning The X Factor. One of her biggest career highlights and shot to stardom came after releasing her 2007 song "Bleeding Love." It topped the charts in 35 countries and her debut album Spirit was the fastest-selling album in the UK just after its release. It was one of four albums Leona released under her contract with Syco. https:\/\/www.youtube.com\/watch?vVzo-EL_62fQ In 2014, Leona posted a message on Twitter and Facebook to announce her departure from Syco. "Simon Cowell has been incredible but at the end of a day it\u2019s a huge label now," she wrote. "I felt like at that stage all they were doing was holding me back from fulfilling my potential, to ask me to do a covers album was... there was no love in it. They weren\u2019t giving me any choice. So no, I said, we\u2019re done now. It\u2019s all good, I\u2019ve still got so much love but we\u2019re done." SEE ALSO: IS SIMON COWELL'S RELATIONSHIP WITH LEONA LEWIS PURELY BUSINESS? Leona wasn't keen on the label's idea of creating a cover album. "Simon probably doesn\u2019t even know what went on in that way, but I felt disrespected and I felt it was a very callous way to act when all I was trying to do was do what I loved" she continued. "I was in limbo and that\u2019s the worst place to be. You can\u2019t leave me hanging on a string." She added that there were times where she was "extremely depressed." https:\/\/www.youtube.com\/watch?vvfbCQ9es0VA Leona signed a deal with Universal Music's Island Records UK after leaving Syco. She departed from Island Records in 2016 after releasing her album I Am. Leona Battled An Illness After Her Split From The Label In 2017, Leona began experiencing an illness. "I was feeling very sick and had chronic fatigue and these really bad pains in my neck and throat," she told Glamour. "I didn\u2019t know what was going on. It was a pretty hard time, and after a bunch of tests, I found out I had an autoimmune condition called Hashimoto\u2019s disease, which affects mostly women." Hashimoto's disease is a thyroid condition where the immune system turns against a person's body tissue. It is seven times more likely to be found in women than in men. https:\/\/www.instagram.com\/p\/CKy2liHADE6\/ "When I was first diagnosed, I was absolutely devastated; I felt very scared and alone until I began to research and understand how others were living with the disease" she continued. "When my symptoms were the most severe, I could hear my body telling me that I needed to slow down. I also started to feel tired during performances." Leona began using natural beauty and lifestyle products and stopped straightening her hair to help reduce the toxins that she is exposed to. Despite going through all of these trials in her life, Leona has still found her place in the entertainment industry. https:\/\/www.youtube.com\/watch?vGm5qOHIy6Zs In 2016, she made her Broadway debut as Grizabella in Cats. And she's not the only talent star to make it on Broadway. Check out the video below for some of the biggest contestants who made it to the coveted Broadway stages. https:\/\/www.youtube.com\/watch?v16wSnebK89g&t2s SEE ALSO: SIMON COWELL BUYS 'X FACTOR' STAR LEONA LEWIS'S HOME & SELLS IT FOR HOW MUCH!? What's next for Leona? The songstress and her husband Dennis Jauch hope to have children in the near future. "'I do want children, but Dennis and I have also talked about adopting," the 35-year-old told Stella Magazine.