My weight, how to look good for upcoming high school ?

So I'm starting high school this year coming up, and i want to be more confident around people. I'm 5'5 and 120 pounds... is that bad everyone says i have a nice body but i want to have a GREAT one ! you know what I mean ? well I eat really good But I'm just lazy and don't exercise like at all... can you tell me what type's i could do ? by the way I'm 13 1/2. and no im not to young to be worrying about my weight, cause I'm not. js