This is the time of year when even people who hate the gym think about going to the gym. Many of us are still digesting whole floors of gingerbread houses, and jeans that fit comfortably in October are now a denim humiliation.

Sweating is a good way to begin 2012. Exercise, like dark chocolate and office meetings that suddenly get canceled, is a proven pathway to nirvana. But if you're going to join a gym—or returning to the gym after a long hibernation—consider the following:

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