A sedentary lifestyle can have severe long-term effects on health. It is associated with an increased risk of chronic diseases, such as obesity, heart disease, and type 2 diabetes. Other consequences include weakened muscle strength, decreased bone density, and poor cardiovascular fitness. Additionally, prolonged inactivity can lead to mental health issues like anxiety and depression. Engaging in regular physical activity can mitigate these risks, enhancing overall health, improving quality of life, and extending longevity.