“Health is a state of complete physical, mental, and social well-being, and not merely the absence of disease and infirmity.” — World Health Organization (1946) Many poets, philosophers, and thinkers throughout history have recognized the intimate link between physical and mental health. The ancient Roman poet Juvenal once declared “A healthy  mind in a healthy body”.

However, until relatively recently, most psychological research has focused on the link between psychological difficulties (e.g., anxiety, depression) and physical health. But things are changing. Over the past few decades, a growing number of studies demonstrate that merely alleviating anxiety and stress don’t necessarily lead to better life outcomes. Positive characteristics, such as optimism, vitality, meaning, and subjective life satisfaction are immensely important in their own right. The related fields of positive psychology and health psychology focus on rigorous scientific investigations of how people adapt to life’s inevitable challenges, and how that is related (or even leads to) a better quality of life. This process of resilience across life is the idea of thriving, successful aging, or flourishing.
See more at: http://www.creativitypost.com/psychology/is_an_optimistic_mind_associated_with_a_healthy_heart