If I say the words "lose weight" the first two concepts likely to spring into your mind are "diet" and "exercise".
There are several reasons for this. One is that you really can't expect to be able to change your body weight for the long term if you are not prepared to make changes in at least one of these areas. Food is the means by which you put energy and nutrients into your body. Physical activity is the means to converting those components into raw work and the development of a fitter more capable physical system (your body).
So you really SHOULD think about exercise and nutrition when your goal is to shed some unwanted pounds of fat, which is the result of adding more energy to your body than can be burned by your metabolism (which is very dependent on your level of physical activity).
But there is another reason why you think "diet" and "exercise". It is because those two concepts are hot on the lips of almost everyone that has ever offered you any advice about how to slim down.
The result is that your subconscious mind has become conditioned to think "diet" and "exercise". Just like Pavlov's dog that salivates at the sound of a bell. You are quite aware that these are the "solutions" to being heavier than you want to be. You don't doubt the truth of these beliefs, and you would expect to see results if only you put them into effect long enough.
But there are usually other accompanying thoughts and beliefs about diet and exercise that are just as important to the weight loss story. They usually go something like this: You hate diets of any kind because being hungry is no fun, and besides you couldn't possibly give up the foods that help you get through your day. You don't have time to relax, let alone to exercise, so don't even think of trying to carve out a workout schedule - it's just not going to happen. You don't NEED to take care of the problem now. Being overweight is a burden, but millions of people deal with it, so you can too.
Carolyn Hansen, the author of The Weight Loss Motivation Bible says that you mind is like software, and that these secondary thoughts are like errant commands in the code, or bugs, that get in the way of execution of the code that you really want to run, which is the set of commands that would have you actually making changes to the way you eat and the manner in which you exercise.
You have to flush out the bugs before you can expect to be able to implement a weight loss plan of action that has a real chance to succeed. Most people fail to recognize this requirement and jump into their next promising eating plan or exercise regime before they have purged their mind of the gremlins that will shortly interrupt their progress.
That's why 95 percent of attempts to lose weight do not result in the kind of outcome that was hope for.
If you want to maximize your chances, begin with your mind. Reprogram it accept nothing less than the result you want. If you need a system to help you achieve that, then be sure to check out Carolyn Hansen's book The Weight Loss Motivation Bible.