Struggling with weight loss *New to the Forums*

Im 18 and a freshmen in college. All my life I have been slowly putting on the weight that I have now (217 pounds). I desperately want to lose this weight and am tired of people calling me "big man" and commenting that I could have a future career as a linebacker. However, every diet and workout routine I have tried has failed. With the exception of only 1. Im struggling to lose the weight and keep it off and just want some help on how some of you have lost you alls weight. With me being in college i am even more concerned about putting on more weight. Any help an motivation would be great.