It is the news that all sloths have been waiting for. Scientists in Germany have found that too much exercise is bad for you and that doing less could lengthen your life. In a new book called The Joy of Laziness: How to slow down and live longer, Dr Peter Axt, retired professor of health science at Fulda University near Frankfurt, and his daughter, Dr Michaela Axt-Gadermann, a GP, say that everybody has a limited amount of "life energy" and that the speed with which it is consumed determines their life span. They argue that high-energy activities, such as pounding...