Physical activity is important for health in several ways: our modern lifestyle has made us sedentary through conveniences like cars and elevators, and physical inactivity is as dangerous as smoking. The document recommends accumulating 60 minutes of physical activity daily for health benefits, though 30 minutes four times a week can also be effective. Physical activity does not need to be strenuous; it can be built into daily life through activities done in 10-minute periods throughout the day. Starting regular physical activity can noticeably improve health over three months.