Never before have so many people run so many miles, or set themselves such ambitious targets, in pursuit of self-fulfillment: marathons, ultra-marathons, extreme adventures. And never before have people had such high hopes of remaining vigorous and active – young in all but name – long after retiring from the work-place. Yet that last goal, perhaps more precious than any of the others, remains elusive. It can be done, but only a few succeed. Horrified by the thought of breaking off his life-long love-affair with running, Richard Askwith began to think seriously about a question with profound implications for every enthusiastic runner: how can you keep running, happily and well, for the rest of your life – ideally, well into your nineties and beyond?