Article by Charlotte Watts and Anna Magee Chronic stress makes us old before our time but the right kind of stress could keep us young. Pioneering new book, The De-Stress Diet will show you the difference and the simple diet, relaxation and gentle exercise you need for a calmer, slimmer future You may not need a book to tell you that relentless stress will make you exhausted, prone to infection and old before your time. But according to a growing school of scientific thought, the right kind of stress could keep you young.  Taken in small doses and at regular intervals, certain physical and mental stressors such as regular tough exercise, mind-bending intellectual work and even pressing deadlines, could not only strengthen your immune-system, they could also help fight some of the physical and mental decline that (you may have noticed) is hard to avoid as you get older. First...