Lifestyle diseases are caused partly by unhealthy behaviors and partly by other factors. Major lifestyle diseases include cardiovascular diseases, diabetes, stroke, cancer, chronic obstructive pulmonary disease, depression, and musculoskeletal disorders. The document outlines the causes, risk factors, symptoms, and methods of prevention for each of these diseases. Unhealthy habits like smoking, poor diet, physical inactivity, excessive alcohol consumption, and high stress levels contribute to lifestyle diseases, while genetic and environmental factors also play a role. Maintaining a healthy lifestyle through diet, exercise, avoiding risky behaviors, and regular medical checkups can help prevent major lifestyle diseases and promote overall wellness.