Honestly, it is. ALL in your head. It begins here and manifests through what you have decided to do. Really this is true for every decision and aspect of life. Life is about setting your mind. It is about determination and decision making. Once your MIND is made up, then you follow through with your actions. It cannot be the reverse.
If you want to lose weight you have to determine to do so. You have to be resolute. It begins in your mind. If you play with back and forth, you will never achieve. Progress is only made through consistency and consistency can only be wrought from the beginning set of parameters you decided to stick to.
There really is nothing more simple than this. Begin with your mind and follow through with your actions. You know what to do. No one can tell you otherwise. You've read every book or article. The guidance you need comes from within. Set your course and sail it. No excuse can deter because you are steadfast. You are smart and capable. There is no fail, there is only to try.
Life is long and we make it difficult. It isn't. Simplify the processes of reaching your goals. Strip away all the voices and rules and make your own. You got this.
Take Good Care.