One thing that I hear from time to time, is that people can't afford a gym membership. I honestly have to say that only a small percent of those people actually cannot afford one, because most people who say they can't, are out clubbing, going to bars, 3 holidays a year and so on. So, some people can simply make a few cut backs if they are serious about getting into shape and improving their health. But here are some ways that you can get fit/lose weight/increase muscle tone whilst not draining your bank account.
1) Walking/running
This is actually completely free, and from what I have personally seen, its becoming more popular. Going for walks or runs is a great form of cardio and can be done at any age. The older you get, the runs will turn to walks, but walking is still a great form of exercise. Both can burn calories - therefore fat, and also increase your cardio - therefore making you a 'fitter' individual.
2) Purchase a stationary bike/treadmill
By going down this route, yes you will have to spend a little bit of money, but it may only work out the same as 2-5 months of a gym membership, and you actually own the equipment. You can pick up an exercise bike for around £60-100, or a treadmill for around £150 and upwards. As I said, you will have to spend a little, but its not a huge purchase, and its a great way of being able to exercise anytime you want. Its particularly helpful if you have a busy work schedule or have children.
3) Purchase some home weights
Again, you will have to spend a little bit of money, but you will be able to get a decent weights set for under £100. This can include some weights, bars and a bench. With this equipment, you will be able to gain more muscle mass (if that's your goal) or use it for circuit training to blast those calories. Some people don't like working out with weights, whilst others do, its all about personal preference.
4) Purchase boxing equipment
Boxing is known to be an awesome workout, burning tons of calories and increase muscle tone. If you look at the top ranked boxers, they are in great shape, and its because of the training they do. You can purchase a punch bag, gloves and a skipping rope for less than £100. If you have a partner, you can purchase some mitts and train together. Again, an inexpensive way to get fit.
5) Purchase a bike
This can be the most expensive method, depending what kind of bike riding you want to do. If you simply want to ride a bike, you can pick up a cheap bike, but if you want to do some cross country riding, you would need to pick up a more expensive bike with a decent suspension system (but even so, there are some great deals out there!). The great thing is you make one purchase and you can use it as many times as you want, and you own that piece of equipment.
I hope these tips help you if you are on a budget but still want to get fit. 'Back in the day', there were not that many gyms around, and these tips were common ways of people getting fit, so they work!