After the last elimination, Alison told the final four contestants — Helen, Mike, Ron, and Tara — that they would be going home for 30 days. At the end of that period, they would come back to the Ranch for one final weigh-in before the finale. The contestants packed up and got ready to face one of their toughest tasks yet: bringing their new, healthy lifestyles to the place where all their problems began. How did they hold up? Read on to find out.

A Happy Homecoming: When they got home, the final four were greeted with huge parties and the love and support of their friends and families. That honeymoon feeling soon wore off, though, as the contestants struggled to adjust to their lives at home without falling into their old habits. To add a little more stress to the situation, a few days after coming home, the contestants all received a Biggest Loser package on their doorstep. When they played the DVD from Alison that was inside, they found out this episode's twist. They still had one more challenge to complete, and it was a killer: a full marathon. That's right, 26.2 miles…and they had 26 days to train for it. (Most marathoners take at least three months to train, and often many more!) Nobody was happy about this one, myself included when I found out about it. I mean, a marathon? Seriously??

Checking Up on the Players: Bob and I knew that the transition to life off the Ranch was not going to be an easy one, so we went to visit our players to see how they were doing. First I visited Mike at his gym in the Detroit area, where he was working out with his little brother Max. Mike told me he was having a tough time taking care of himself while trying to get Max healthy, and I helped him get his focus back. Then I stopped by Tara's house on Long Island, where her room looked like a tornado had hit and her life, as she described it, was chaos. I had her sit down with me, enjoy a glass of wine, and talk about how she was feeling. She was obsessively exercising and putting lots of pressure on herself to be perfect, and I had to talk her down and encourage her to find balance in her life. When I dropped in on Helen in Lansing, Michigan, I could see that she needed the same message. She was driving herself nuts trying to be a superwoman, running herself into the ground so she wouldn't let herself or anyone else down. We took a timeout, and I reminded Helen that it was okay to enjoy her life — after all, that was the point of everything she'd been through! Bob paid a visit to Ron, where he helped him and Mike get Max on the right track with exercise and healthy eating.

The Toughest Challenge Yet: At the end of the 30 days at home, the contestants returned to Cali to face the marathon. When the race began, Tara and Helen took off, while Mike, who was hampered by a hip injury, walked with his dad Ron. None of the contestants were sure they could go the distance, but along the route waited lots of inspiration, from family members who joined in for a few miles to former Biggest Loser contestants who gave much-needed pep talks. Season 5 winner Ali Vincent surprised Tara at mile 13, where she told Tara that watching her win all those challenges this season was a huge inspiration to her. Season 6 winner Michelle Aguilar greeted Helen at the halfway point, and Season 5 at-home winner Bernie Salazar showed up to cheer on Mike, who was disappointed that he had to walk. Ron's bad knee started giving him trouble around mile 5, and the rest of the journey was a battle. But with the help of Season 4 at-home winner Jim Germanakos, Season 6 at-home winner Heba Salama, and the rest of the former Losers, he finally crossed the finish line. In the end, Tara won the race, but everyone was incredibly proud to have completed a feat that a few months ago they didn't think was possible. It was truly inspiring to see.

The Final Weigh-in: The players didn't have much time to pat themselves on the back for their marathon finishes — soon they were back at the Ranch for their last weigh-in before the finale. The two players with the highest percentage of weight loss would be guaranteed a spot in the finals, while the two who fell below the yellow line would be leaving their fate in America's hands. Ron got up first, losing 10 pounds over the 30 days at home to bring his season total to 151. Mike followed his dad, also losing 10 pounds to bring his weight down to 214 pounds. Helen went next, losing 7 pounds, which represented a higher percentage of weight loss than Ron and pushed him below the yellow line. Tara went last, and as usual she blew away the field, locking in her finalist status with a loss of 10 pounds. (That's a percentage of 5.92 — the highest percentage lost in one weigh-in in Biggest Loser history!) That left Mike below the yellow line with his dad. They went to the confessional, where Ron pleaded with America to vote to keep Mike in the game. Now it's up to viewers everywhere to decide which one of them stays in the running — be sure to visit www.nbc.com before 9:50 p.m. ET TONIGHT to make sure your vote is counted!

Next Week: It's the episode we've all been waiting for: the LIVE FINALE! The results of America's vote will be announced, and then the third finalist will face off against Helen and Tara for the top prize. The at-home contestants will be back to compete for their prize, too — you don't want to miss their incredible transformations. Be sure to tune in to NBC at 8 p.m. ET next Tuesday night to see who's crowned the Biggest Loser!