We've all heard the saying, "You are what you eat." In essence, what you put into your body is what your body will use in the construction and replacement of its cells, hormones and neurotransmitters. Quite literally then you are composed of the very food you consume. It is logical then to say a body constructed of junk food and low nutrition will be inferior to a body constructed from wholesome food in the correct quantities. And consider that most cells in your body will be completely replaced within 7-10 years, so do you want a body built from Twinkies and soda or whole grains, fruits and vegetables? The former will be less able to adapt to daily life stresses and will be more susceptible to sickness and disease.
However, equally true and important is the mental axiom that you become what you most often think about. Scientific studies have shown that repetitive thoughts actually create chemical and physical changes in the brain. Specifically, neural connections are made that change the shape and function of the brain. An analogy could then be made that negative thoughts are like junk food and positive thoughts are like nutritious food. If your spending more time processing negative thoughts than positive ones the resulting neural connections and neurochemistry will be that of an unhealthily stressed brain. Of course it is almost impossible not to have some negative thoughts, but we should try as best we can to replace our thoughts of hatred, guilt, and frustration with compassion, forgiveness, and humor.
Taken together, choosing a healthy diet, exercise, and replacing negative thoughts with positive, productive ones will help us to achieve our optimal physical and mental health.