Human beings may have evolved throughout the centuries but many of our basic needs for a healthy life have remained unchanged: sleep, food, sunshine, physical activity, contact with other people. Although modern gadgets have made our lives more comfortable, our bodies have not really altered much down the years. This has led to an anomalous situation in which our desire for convenience and comfort is actually causing us harm both in the over-consumption of junk food and a lack of physical exercise – including ordinary walking.