no sensible person can deny that sport will help people keep fit and stay healthy.
What, you mean no one could point out that many sports are quite dangerous and can routinely result in the players suffering from serious injuries, the list of which can be quite extensive: orthopedics.about.com/cs/sportsmedicine/a/football.htm
By doing exercise everyday like jogging, swimming, they can work off fat and burn calories which they took in variety of food during a day.
Well, yes, but these can be done non-competitively, outside of school.
Consequently, the youngsters become more confident because they dare to say their personal ideas in workshops, more sociable and extrovert.
It would be nice if you could back this up with some research and statistics.
Your body paragraph should be divided into several smaller paragraphs that each deal with a single reason in support of your thesis. Also, many of these reasons seem to be good reasons why one should play sports in general. You might want to address why schools specifically should incorporate them into their curriculum.