The culprit? Inertia. What we have gained in convenience from labour-saving devices over the past half-century, we have paid for in terms of a sharp decline in physical activity.

• 罪魁祸首是谁?懒惰！半个世纪以来，我们从各种节省人力的设备中得到很多便利，但这是以我们身体活动的大大减少为代价的。