MORE FROM THE BIGGEST LOSER'S HEAVIEST CONTENDER

The Biggest Loser will this season have its heaviest contender ever, 29-year-old social worker Shauntina "Shay" Sorrells.

When Sorrells was asked what she believes is her greatest challenge, she told etonline, "I am my biggest challenge: All the "I can'ts." The "I may not be able to do it" that walked into the gym with me that first workout, but they beat it out of me. I walked out, I survived and I did things that I never thought I was going to be able to do, like an hour on the treadmill at 476 pounds. That seems insane. Some people at 476 pounds can't get out of their bed. So, I want to inspire them and get them out of bed."

Sorrells told et that the best advice she has received on The Biggest Loser ranch came from Jillian -- who told her simply, 'Don't quit.

As for her first workout, Sorrells described it as tremendously difficult. She explained, "I mean mentally, physically, so many levels. You are: Am I going to be able to take another step? Am I going to be able to lift my leg? Am I going to be able to do what they want me to do? There are so many expectations you feel from the trainers that you think, "I am never going to be able to do that. Am I going to be able to survive? Am I going to be able to do this tomorrow? Am I going to be able to crawl to the house? What is going to happen?" But you put one foot in front of the other.

"There was one moment when I gave up. I thought, "[Jillian] is crazy. She does not understand that I am 476 pounds and I can't climb this ladder. I walked out. I had already done it, but then she wanted me to do it again. I was, "I can't." I walked out and then I took two moments, and went, "What is your problem? You went this far to be here, what is going on?" I was talking to myself: "Are you doing it for her, because that is not going to get you very far? Are you doing it for the people at home because that is not going to get you very far?" I had to refocus and remember I was doing this for me and go back in there and do it again. That is what I did. People told me I would quit in the first five minutes with her, but I made it nine minutes!"

The first episode of "The Biggest Loser" will air on September 15th at 8 p.m.