8lb weight loss

I have been trying to lose 8lbs for the past 5 years. It just occurred to me that my thoughts are contributing to this. My thoughts are: “this is so hard”, “I can’t do this”, “I look pretty good for my age”, “the last 8lbs are the hardest to lose”, “I already watch and limit what I eat”. How do I create and maintain new thoughts that will foster motivation and beliefs that this goal is achievable? Thank you .