I will tell you a secret,there is no secret. Motivation is not something you can find somewhere, it only comes from within. I sound like an a hole I'm sure but, until you want it bad enough you won't have it.
Unless the pain is greater than the pleasure, you will find it difficult to move forward. I don't mean just physical pain, but emotional as well. I really encourage you to try weigh watchers, you don't diet, it simply helps you learn portion control.