It's always easier to do something when you do it with a group.
Here's a novel idea - the RunToTheFinish blog reports about how a group of folks are committing to clean and lean foods for 28 days. When you do an activity like this with a group, it helps keep everyone accountable.
One of my good friends who is a fitness instructor likes to distribute daily small workouts people can do each day of the month beyond her classes. She shares the workouts with her regular students and they often check with one another, "Did you do the workout today?"
Living a healthy lifestyle is especially easier when done with a group.