Shortly after I started losing weight, I decided to get a group of co-workers to lose weight as well. We decided to wager $40 to see who could be the most successful. After 2 months, whoever loses the highest percentage, wins the competition, and $400!
They money is a great motivation. But even though my co-workers and I are competing, we still motivate each other. When others bring donuts for the office, we encourage each other to say no! It helps when you have others going through the same challenges you are.