Healthy immune system helps in enhancing the quality of life and reduces the risk of infectious disease. Chronic disease increases the risk of immune system impairment. The article reviews the evidence on risk factors causing immune system imbalance and articulates the complex nature of the relationships between immune system risk factors, chronic disease, and infectious disease to highlight the importance of lifestyle choices. Finally, some evidence is presented on mind–body interventions and lifestyle choices for enhancing the immune system function.