The fitness craze is going gangbusters, with gym attendance up 23% since 2001, to 41.3 million, according to the International Health, Racquet and Sportsclub Association (IHRSA). And most new recruits sign up in January — the busiest month for fitness clubs. That's when well-intentioned souls trying to stick to their New Year's resolutions flood their local gyms, often resulting in long lines at the treadmill, overtaxed gym staff and towel shortages in the locker room. But it won't be long before the throngs thin; most resolution makers trip up in the first 90 days, says Alan Marlatt, director of the Addictive Behaviors Research Center at the University of Washington. And indeed, that's what clubs expect. "They bet on it," says Meg Jordan, editor of American Fitness, adding that most gyms count on a 20 to 30% dropout rate.

In the meantime, there are ways to avoid January overcrowding and make it past the 90-day hump. When selecting a new gym, visit the facility during the time of day you're most likely to attend. If it's crowded, check to see whether waiting lists and time limits on machines are enforced or whether it's a free-for-all.