Take the stairs instead of escalators and elevators.
On the weekend, walk everywhere, even faraway places (avoid polluted areas as much as possible).
Do moderate exercise for 2.5 to 5 hours a week, with some of it in the vigorous range. Most of the beneficial effects appear to be caused by the first 2.5 hours of exercise, making the additional exercise optional.
Use weight training or weight-free exercises to strengthen all muscles.
To maximize muscle growth, consume at least 30 grams of protein in a single low-carb meal 1-2 hours after a relatively intense weight-training session.