Danni Allen, who won season 14 of "The Biggest Loser" after shedding 121 pounds, is terrified she'll regain the weight, so she's training for the 2013 Chicago Marathon as a way to maintain her incredible weight loss.
"One of my biggest fears is putting the weight back on," Allen, 26, told People. "So I have set up some goals for myself. I want to run the Chicago Marathon [in October], so I'm signing up for that."
Danni was crowned "The Biggest Loser" on live TV March 18 after losing a whopping 46.9 percent of her body weight, slimming down from 258 pounds to 137 lbs. Allen, who went from a size 20 to a four, says the dramatic makeover has changed her physically and emotionally.
"I am different in every which way possible," says Allen. "The physical transformation is right in front of you, but the mental change that I've gone through has been amazing. I've been able to change who I am going to be."
Danni, an advertising account coordinator from Wheeling, Ill., won the $250,000 grand prize, and plans to use some of the money to take two of her "Biggest Loser" competitors (runner-up Jeff Nichols and his girlfriend Francelina Morillo) on vacation with her.
"The one thing that Jeff and I promised each other is that we would reward the other with a vacation," says Allen. "We did this together and I'm happy to keep my word and take Jeff."