Biological and social sciences have long held that our biology and environment, along with our life experiences, combine to form the basis of how we experience and interact with the world. For hundreds of years, the scientific and medical world believed that our genes were the predominant factor dictating the structure and function of our physiology. Specifically, the brain was viewed as fixed in both its structure and functioning after an early stage of development that ended in childhood. Such thinking led the way to the belief that our physical as well as our mental health was immutable and could not be influenced by our behavior.
Over the past several decades, scientific studies have shown that the brain is not hard-wired in childhood, and we are not doomed by our DNA or our early and later life experiences, and that the brain is pliable and changeable throughout our entire lifetime. In fact, the latest research in genetics, neuroscience, and psychology points to individual’s ability not only to alter their behavior* but to directly affect the development and functioning of their own physiology, including the development, structure, and functioning of their brains. That is, how we think about our thoughts (meta-cognition), how we experience our thoughts, and how we think about our experiences has a dramatic influence on our emotions and our behavior and, in fact, can change our physiology, including the structure of our brain.
*Behavior in this sense is anything a human being does. Internal behavior is behavior that is unobservable to others (e.g., thinking, emotions, urges, memories, heart palpitations, etc.) External behavior is observable (e.g., talking, moving, sweating, etc.)