Like most Americans, I've eaten too much this holiday season. Too many bakery cookies, too much bread, too much sugar. But on Jan. 2, I'll hit the treadmill after work like everyone else who pledged to drop 10 pounds in the new year.

More than 50 million Americans belong to a gym, according to a 2012 health club consumer study by the International Health, Racquet & Sportsclub Association (IHRSA). There were 30,500 health clubs in the U.S. last year and revenue for the industry totaled $21.8 billion.

Gyms are a big business and membership consultants are out in force now to sign up as many new members as possible. Before you sign the dotted line on your new contract, there are several important things to keep in mind. The Daily Ticker spoke with Tom Holland, a personal trainer, former gym owner and author of the book Beat the Gym, about the biggest secrets of the fitness industry.

1. Gym initiation fees are negotiable

"Don't pay it," says Holland. If the salesperson won't budge "try cutting it in half. If you don't get what you want, walk away."

2. Gyms don't really want members to show up

"Gyms are about the numbers...they're not looking out for your best interests," notes Holland. "If everyone who has a gym membership actually used the gym, the owners would be in trouble. Gyms just want to lock clients into contracts and hope they don't actually show up."

More than 60% of people who join a gym never return after three months, according to Holland.

3.  Never sign a gym contract in the gym

Once you've settled on a gym (pick the closest one to your house or apartment, Holland advises), never sign the fine print in person. Take the contact home, review it and read every word carefully. Gym contracts are hard to break and Holland recommends avoiding them completely, if possible.

"Gyms may be willing to take 10% off the cost if you can pay the full year's fees upfront," he explains. "Gyms have more wiggle room than you think."

4. Get free stuff

If you're debating which gym to join, ask for a free pass. Some gyms are even willing to let prospective clients have unlimited access to classes and equipment for a week.

"Take the gym for a test drive," says Holland.

A lot of gyms also offer freebies online, so always check a gym's website for special offers. Staff trainers are also often willing to meet with gym members for a free session.

5. Personal trainers are promoted on the basis of sales, not certifications

Holland says only 12% of gym members work out with a trainer yet personal training "is where gyms make all their money." The most experienced trainers may not be the best and the most expensive trainers may not have a long list of credentials. If you are serious about personal training and can afford it, the best way to find a trainer is to meet him or her, discuss your fitness goals and check out the trainer's clientele. If you like what you see, then go forward.