Lifestyle diseases are caused by modern lifestyles and unhealthy habits such as poor diet, lack of exercise, obesity, stress, smoking, and alcohol consumption. Some major lifestyle diseases discussed include heart disease, COPD, diabetes, high blood pressure, depression, and breast cancer. Risk factors include eating junk food, lack of physical activity, obesity, stress, poor sleep, smoking, and excessive drinking. Maintaining a healthy lifestyle through diet, exercise, managing stress, and avoiding tobacco and alcohol can help prevent these diseases.