1. Sports. Most of us live within walking distance of a park or community center. At the very least, these parks should have a tennis or basketball court which are perfect for cardiovascular exercise. The great part about using sports for cardio is that you don't have to pay very much for the equipment and if you're having fun, you won't realize how much time you're actually devoting to exercise.
2. Swimming. Swimming is also an exercise you can do for free at the community pool. Swimming provides low impact cardiovascular exercise for those who have joint problems. During the summer it's also a fun way to get children to exercise instead of playing video games.
3. Run, Walk or Jog. One of the few exercises you can do without any equipment (except for shoes) is run, jog and walk. These three activities are very good to build up your endurance, burn calories and get into shape. For more motivation, you can adopt a dog and take it on runs or walks. It'll be more than happy to help you out.
4. Use Your Body Weight. Body weight exercises are also an area in which you need very little equipment. You can do sit ups, pull ups, push ups, squats and lounges. These exercises will help you build muscle without going to an expensive gym. You can do most of these in the comfort of your own home in front of the TV. You can also buy some inexpensive weights to enhance some of these exercises.
5. Hard Labor. Some activities that you need to do aren't usually seen as exercise but still force you to work hard. Yard work, housework and car work can all count as exercise if you do them often enough and get your heart beating quickly.