Looking for motivation!!! :)

I was wondering if any high school/college students had some motivational before and after pictures. I have been trying to loose weight for quite a while now and always start off good and then eventually stop. I am 5'9'' and currently weigh 180 lbs with a goal weight of 140 lbs. I would appreciate any advice as to how to maintain good grades ( I am in almost all AP classes) while still loosing weight. Thanks in advance :)