If you're determined to save money, find ways to integrate exercise into your daily routine and don't join a gym at all.
This makes it more likely you'll keep it up if it is a natural part of your day.
You could set aside half the money you would spend on the gym towards some of the options below.
I know it's not always practical, especially in the winter, but here are a few things you could do.
Walk to work
Take a weekly walk with the family.
We do a minimum of 3 miles/week at the weekend, more if weather is good.
Take the stairs
not the lift/elevator Do the odd exercise at your desk (unless you make funny faces when you exercise)
Park further away from the entrance to buildings Get off the bus one stop earlier Go for a jog in the morning
Make an exercise routine out of unpacking the shopping, e.g. do
a few bicep curls with a can Get a dog "bench press" your kids,
i.e. play games that involve lifting them in various ways (helps if they're younger)
Play social sports like football (proper football,
none of that girly stuff with shoulder pads) or doubles tennis/badminton at the local sports centre.
Court charges split 4 or 10 ways are much less.
If you mainly do one type of exercise, like rowing, buy a rowing machine.
An OK one typically costs about 5-10 months membership.
And it is a one off purchase you won't use instead of a monthly recurring expense you won't use.
One of the other answers makes a good point.
Gym membership can be cost effective if you go regularly, but don't kid yourself that you'll suddenly go 5 times a week every week if you've not done much regular exercise.
If you are determined to join a gym, here are a few other things to consider.
Ask about an introductory trial.
You may be able to get a 1-3 month trial.
If you do, keep notes of every visit so you can evaluate if you really are getting value from it.
You may be able to get a discount through work, for example my employers have negotiated a discount with some local gyms.
Don't join up at the beginning of a month, especially January.
Like when buying a car, the reps may be keen to get commission near the end of a month/week. Get together with some friends who are keen and see if you can negotiate a discount for the group to join.
You may also find it easier to keep in the habit if friends are going too.
money.stackexchange.com/users/32/Rich Seller
Shop around for Gym January is a great time to look because that's when most people join and the gyms are competing for your business.
Also, look beyond the monthly dues.
Many gyms will give free personal training sessions when you sign up - a necessity if you are serious about getting in shape!
My gym offered a one time fee for 3 years.
It cost around $600 which comes out to under $17 a month.
Not bad for a new modern state of the art gym.
money.stackexchange.com/users/169/HitLikeAHammer
Try a gym for a month before you sign up on any contracts.
This will also give you time to figure out if you are the type who can stick with a schedule to workout on regular basis.
Community centres are cost effective and offer pretty good facilities.
They have monthly plans as well so no long term committments.
money.stackexchange.com/users/None/
Find a physical activity or programme that interests you.
Memberships only have real value if you use them.
Consider learning a martial art like karate, aikido, kung fu, tai kwan do, judo, tai chi chuan. :-)
Even yoga is a good form of exercise.
Many of these are offered at local community centres if you just want to try it out without worrying about the cost initially.
Use this to gauge your interest before considering more advanced clubs.
One advantage later on if you stay with it long enough - some places will compensate you for being a junior or even associate instructor.
Regardless of whether this is your interest or if the gym membership is more to your liking real value is achieved if you have a good routine and interest in your physical fitness activity.
It also helps to have a workout buddy or partner.
They will help motivate you to try even when you don't feel like working out.
money.stackexchange.com/users/19/Zephyr
The gym I used to use was around £35-40 a month, its quite a big whack
but if you think about it; its pretty good value for money.
That includes gym use, swimming pool use, and most classes Paying for a gym session is around £6 a go, so if you do that 3 times a week, then make use of the other facilities like swimming at the weekends, maybe a few classes on the nights your not at the gym it does work out ok
As for deals, my one used to do family membership deals, and I think things like referring a friend gives you money off etc.
They will probably also put on some deals in January since lots of people want to give it a go being new year and all
money.stackexchange.com/users/86/James
Look for discounts from a health insurance provider, price club, professional memberships or credit cards.
That goes for a lot of things besides health memberships.
My wife is in a professional woman's association for networking at work.
A side benefit is an affiliate network they offer for discounts of lots of things, including gym memberships.
money.stackexchange.com/users/91/MrChrister
I came across an article posted at Squawkfox last week.
It's particularly relevant to answering this question.
See 10 Ways to Cut Your Fitness Membership Costs .
Here's an excerpt: [...]
If you’re in the market for a shiny new gym membership, it may be wise to read the fine print and know your rights before agreeing to a fitness club contract.
No one wants to be stuck paying for a membership they can no longer use, for whatever reason.
But if you’re revved and ready to burn a few calories, here are ten ways to get fitter while saving some cash on a fitness club or gym membership.
Yay, fitness tips!
[...] Check it out!
money.stackexchange.com/users/3/Chris W. Rea
Do gyms ever negotiate or haggle on price?  Do they always insist on a term commitment?  Are there any tips and tricks on ways to avoid paying through the nose?
How can I save money on a gym / fitness membership? New Year's Resolution is to get in shape - but on the cheap!
money.stackexchange.com
<cost-cutting><memberships>
money.stackexchange.com/questions/666
money.stackexchange.com/users/14/Nat_Rea
There can be discounts from health insurance providers or through an employer. January is a good time to shop around for the best offer. You could also get together with friends and negotiate a discount. You might also be able to get a free trial before you sign up and look into community centres that are much more cost effective. Ways to save on gym membership include shopping around and trying to negotiate deals. You could even try and negotiate a group deal with friends. Make use of any trial periods and never join a gym at the beginning of a month. You could also check out any local community sports facilities, which are likely to be cheaper.
Shop around and look to negotiate prices or offers with fitness centres. You may even wish to negotiate a group deal with friends. Ask about any trial offers so that you can try the facilities before making any long-term commitments. Don't join a gym at the beginning of a month. Try looking at community sports facilities, which are usually cheaper.