Answer:
Lifestyle is the internal influence that most affects physical activity. An individual's lifestyle, including their daily habits, routines, and choices, can significantly impact their physical activity levels. For example, a sedentary lifestyle that involves little to no physical activity can increase the risk of various health problems, such as obesity, heart disease, and diabetes. On the other hand, an active lifestyle that involves regular exercise and physical activity can have significant health benefits, including improved cardiovascular health, increased energy levels, and improved mental well-being. Therefore, an individual's lifestyle can play a crucial role in determining their physical activity levels and overall health.