Have you tried many diets, workouts, exercises, shakes, gyms & environments. Do you still struggle to attain that change?
If you do not believe you can accomplish something and are not prepared to do what it takes to get that goal how much effort will you put into reaching it?
It is our internal belief that will determine success. If we do not believe we can do something then the action required to reach that goal will be minimal and your likelihood of losing weight or creating change, will be significantly affected.