How your mind works determines how you live your life. It determines whether you are at conflict with the world, or at peace with it. It determines what and how you eat, how you react to all situations, what you believe you are capable of, and what your limitations are. It determines what you can and cannot do without, what you do and don't do, what you are attracted to, and what you are afraid of. It determines what you consider to be important and unimportant, what you do with your life, and what you think life is about. It determines whether you blame or forgive, hate or love, and it determines your level of inner happiness, joy, and completion.
How your mind works determines literally everything about your life, and the relationship you have with the rest of the world.
Absolutely everything is a perception (that can be changed), and absolutely everything stems from the mind. It's not what's going on "out there" in the external world that matters. It's what's going on "in here" in your mind and heart that matters. Everything has to do with the ingrained programming of your mind.