I really like this guy but need help!?

k , there is this guy i really like... he is really cute and nice... he is my age but started school early so he is in the year above me... he won't go out with me... what r some ways that i could get him 2 rethink his opinion of me? I love him so much and all i do is stare at him dreaming he is mine but back 2 reality, he doesn't like me... only cuz i'm a little overweight and not as pretty as he would want... what can i do 2 change his opinion of me? I can't get him out of my mind!!! Help!!! Please!!!