The final four contestants go home for 30 days, reunite with friends and family and experience firsthand the challenge of continuing to make diet and exercise a priority back at home. Contestants also learn from host Alison Sweeney what their final challenge of the season will be - running a full marathon when they return to the ranch for their final weigh-in. Completing the full 26.2 mile course will be their toughest challenge yet, but cheering them on along the way are some past season "Biggest Losers"- grand prize winners Ali Vincent and Michelle Aguilar, plus "at home" winners Jim Germanakos, Heba Salama and Bernie Salazar. And as an added incentive, each player who finishes the marathon will get $10,000 to donate to the charity of their choice. Later, it's the very last "last chance workouts" with trainers Bob Harper and Jillian Michaels before a final weigh in determines who the two definite finalists will be - and which two contestants fall below the dreaded yellow line, leavin