проверьте пожалуйста эссе по английскому "for and against doing sport"?

not to, а не to not в певрой строке
To с help не употребляется. Например, help me,  а не help to me.
To sum up, sport is necessary или ещё что-нибудь в этом роде. Must употребляют в сочинении с глаголом, а не как существительное.

Sport is one of the essential parts of a person's life. It helps us to not only gain good health but gives our lives interest, enthusiasm and excitement. Nevertheless, there are people who think that sport is harmful. 
In my opinion, sport is good for the body because it makes you burn calories and makes you increase your muscle mass to have a fit body. Besides it helps the person to become organized and better disciplined, if he plays in a team sport. Finally, it has psychological benefits of reducing stress. 
However, there are some drawbacks of doing sports. Heavy workouts can be dangerous and even lead to serious health issues, because they take a lot of energy and could lead to exhaustion. Although it is very beneficial to do exercise regularly, abuse has its downside because as a result you may get injuries or cardiovascular diseases. 
Furthermore, light workouts bring a lot of benefits to health and they are very useful. Besides, if you do sport with your friends it is more fun and pleasurable. 
To sum up, sport is a must if you want to keep yourself healthy. However, it has to be said that some physical activities may be even dangerous. That's why sports must be done with carefulness and without over exercise, which leads to injuries. 

Некоторые предложения всё ещё не нравятся но весь текст переписывать лень ^^