We've had Thanksgiving, Christmas, and New Year's Eve in rapid succession. You've been partaking of the fruits of your labor and enjoying the festivities with loved ones--at least until January 1. Then you immedately become a disgusting pig who should get some of that blubber off.
You want to join a gym? Good idea! Go ahead and visit a commercial gym. Pay your membership fee. Workout once. Then repeat this process next January.