Every January, millions of Americans, brimming with optimism and a little extra belly from the holidays, commemorate the New Year by making an unfamiliar urban trek. They go to the gym. One in eight new members join their fitness club in January, and many gyms see a traffic surge of 30 to 50 percent in the first few weeks of the year. Stop by your local gym soon after January 1st, and the ellipticals will be flush with new faces. But next thing you know, it will be April, our gym cards will be mocking us from our wallets, and our tummies will have sprouted, on cue with the tree buds.

Gyms make most of their money from two sorts of people: 1) absentee members and 2) super-users who pay not only the monthly fee but also for the add-ons, like trainers and classes, all the way down to the whey smoothies. Unfortunately, most of us fall into the absentee member category. In January, our cup of willpower overfloweth. But by June, the odds that you've kept your New Year's resolutions fall to under 40 percent.

Possible Preaching Angles: (1) Discipleship; Endurance; Lukewarmness—When it comes to following Christ, are you an absentee member? Have you started with Christ but slacked off? (2) Church; Membership—Gyms may thrive on absentee members but the church can't.