Diet and exercise are as much about mindset as about fact and science.  How you think and feel have a major impact on success, as much as any well executed plan does.  As soon as you let go of the pre-conceptions, beliefs and black and white thinking about diet and exercise, the better the degree of success you will have in the long term.

The best long-term approach to health is to spend the time now learning and understanding how your unique metabolism responds to diet, exercise and lifestyle, then build an approach that fits you specifically.  Learn and understand how your psychology impacts your physiology. Does stress make you skip meals and then binge? Does it make you eat uncontrollably? Does it make you over or under exercise?

Equally important, acknowledge the fact that your personal preferences matter, very much so. The best approach is to include as many of the things you love into your lifestyle while still achieving results. The most damaging thing you can do is to forbid foods that you love. It is like saying "don't think of a white elephant", it quickly becomes all you think about. The same analogy applies with food.  Deny an item indefinitely, and you’ll become fixated on it repeatedly.

Take the time to understand these unique attributes of yourself, and from there construct a lifestyle and plan that works for the long term.  This will lead you down a happier and more successful path than if you put your belief in magic potions, and perfect diets.  There truly are no successful, long lasting quick fixes.