If you're like virtually every other American who ends the holidays feeling like a stuffed bird, you've probably resolved to exercise and lose weight this year. If you're shopping around for a gym membership to help you achieve those goals, make sure you get your money's worth from your investment of time and money.

The first and most obvious point: You have to use the gym to make your membership dues worthwhile. There's a reason that many personal-finance advice columns urge you to cancel your gym membership if you're not using it.

As a nation, we spend billions every year trying to lose weight. A recent Consumer Reports article about fat-blocking drugs put the total at $41 billion annually. Weight Watchers (NYSE:WTW) may lay claim to the honor of being the best-known brand in weight-loss programs. The online service eDiets.com (NASDAQ:DIET) has tried to capture a portion of the market by licensing the most popular diets. The Motley Fool CAPS community has given Life Time Fitness (NYSE:LTM), which runs large professional and recreational facilities, a four-star rating thanks to expectations that it will outperform the market.

Lest all this make you feel like an unhealthy victim of the diet industry, know that there are lots of regular gym users chugging along on treadmills and spinning on stationary bikes, and they squeeze every dollar from their monthly dues. If you want to join their sweat sessions, here are some things to keep in mind:

  • Visit and work out at least once at any gym you're interested in joining. If possible, get a free pass or a short membership that will let you visit for a week or two. That will give you the chance to find out whether the location, hours, and class schedule work for you.
  • Ask about all the fees, including sign-up fees. Find out whether the monthly rate they give you is an introductory rate or the permanent rate. Ask whether you can have a discount if you pay in a lump sum, instead of monthly. Ask your friends if any of their gyms have referral discounts. It's a good time of year to spot some bargains among gyms that are hoping to sign up everybody who has made a New Year's resolution to exercise. Don't be afraid to try a little negotiating if you know that a competitor is offering a better deal.
  • If you're uncertain whether a certain gym is right for you, resist the urge to fall for demands that you must sign up immediately to get this "once-in-a-lifetime, limited, bargain-basement" offer. If you haven't had time to understand the terms of the agreement, you may sign up for something you'll later regret. If the gym is a reputable business, it'll want you as a customer whether you sign up right this second or think it over for a few days.
  • Look around for other discounts. Some employers will subsidize part of their employees' gym memberships. A few doctors have even jumped on that bandwagon, arranging discounts for their patients to help keep them healthy.
  • Make sure you understand the terms of your contract, including its length and the terms of its renewal. Some may renew automatically, on a monthly or annual basis. Ask also whether you can cancel the contract before it ends and whether you would pay any penalties for doing so. Think twice about any contract that lasts longer than a year. Your life may change a lot in 12 months, making any one gym less attractive.
  • Keep going. You'll get the most out of your membership if you become a regular user. If you want a little motivation, figure out what you're paying on average for each visit. Then, when you're tempted to sit on the couch and watch TV, you can remind yourself just how much money you're wasting by skipping a session.
  • Use the free stuff that frequently comes with a membership. Often you'll get a few sessions with a personal trainer. Try out all the classes. Make a little time to relax in the sauna. The more you get out of the experience, the more you'll be motivated to keep coming back.

Lastly, ask yourself whether an all-purpose gym is the right place for you. Gyms can be great for aerobic equipment, group classes, and weight training. If you'd rather devote yourself to yoga, swimming, or karate, you may be better off spending your money specifically on those pursuits. If you do what you love, you'll be more motivated to keep it up.

If you can multitask, you can even do some reading while you're churning along on the elliptical machine and make 2007 a healthier year for your personal finances. Try the Motley Fool Green Light newsletter service free for 30 days. The January issue has lots of advice for helping you achieve your financial resolutions this year. Think of it like a personal trainer, but without the sit-ups.

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Fool contributor Mary Dalrymple hates sit-ups and welcomes your feedback. She owns shares in no company mentioned in this article. The Fool has a disclosure policy.