Over the last decade, the focus on diseases has shifted from communicable to Non-Communicable diseases, such as cardiovascular diseases, diabetes, cancer and respiratory tract infections. Chronic diseases are linked to life style choices such as unhealthy eating habits, physical inactivity, smoking and drinking. Unhealthy life style choices cause imbalance in the physiological systems leading to disease formation. In this note, we discuss the role played by three physiological systems, namely, nervous system, endocrine system, and immune system to maintain body balance (physiological homeostasis) and keep the diseases at bay. Chronic diseases are on the increase in Indi and developing countries.