Why do you have to exercise?

Exercise burns calories, fat, and build muscle. When on a diets exercise can help you lose weight faster, keep it off, can lead to healthier diet choices ,and can suppress junk food cravings. Also exercises such as running can release endorphins to the brain which can make you feel happier. The minimum exercise a person should get a day is about 30 minutes.
So u don't get fat and lazy and eat for fun. dosent sound like you've exersised befrore:)