Why is mental health just as important as physical health

Why is mental health just as important as physical health? Your thoughts become reality, if your thoughts are incredibly negative the reality of your physical condition will start to reflect that, over time your body will start to take on the physical appearance of how you look at yourself, once this starts to happen various diseases will start to flourish inside of your body causing it to internally destroy itself. Over time as the symptoms of depression start to become more noticeable and develop into full on clinical depression, your behavioral health starts to change, once this happens the mind starts to become incredibly negative, once the mind takes on this negative view of itself you start to develop various different diseases and pain throughout the body. Negativity and negative thoughts destroy the body, just like you can heal yourself with positive thoughts you can destroy yourself with negative thoughts, little by little your telling the body to dismantle itself so various diseases get by your defenses and start to manifest.