Starting over... again :/

I started MFP in late March of 2011 and had great success in my first few months. Then, I went on a vacation in May and struggled to get back in the swing of things. A lot of my MFP friends dropped me (not that I blame them) because I just completely fell off the band wagon. I've done every diet out there, I even had lap band surgery, and I've never had lasting success. WELL WORLD, this is the time. I'm changing my life, and for once, I'm going to like what I see when I look in the mirror. I have over 100 lbs to lose. But, I KNOW I can do it. Seven of my family members have bought into a "biggest loser" family challenge. It was $10 to buy in, and every week we weigh in, if we lose, we don't pay, if we stay the same weight, we pay $2, and if we gain, we pay $10. I HAVE to lose every week. Plus, I could use the money. The winner (whoever loses most) gets 60% of the pot, 2nd gets 30%, 3rd gets 10%. What are all of you doing to stay motivated?