1. In an isometric exercise you tighten your muscles without making any movement. These exercises make the muscles attached to your bones larger and stronger.
2. Tighten a muscle and hold it for five seconds
3. An isotonic exercise is when you contract your muscles to produce a movement. These are also anaerobic exercises. They do not burn fat but bigger muscles burn bigger calories.
4. Lifting weights is an isotonic exercise some people do to get stronger. But lifting weights is not a good idea until you've stopped growing.

Some things that you can do to start improving your health would be to walk or ride a bike to a friends house instead of getting a ride, taking the stairs at a store rather than the escalator or elevator, or turning on the radio and dancing. Remember something is better than nothing, and keep it fun!

You should also be a smart exerciser. If you feel any of the symptoms you need to STOP exercising: Pain, feeling dizzy or faint, nausea, severe fatigue.