We are entering an era of unprecedented longevity. Half of all 5-year-olds in the US today can expect to live to 100. Ageing populations are commonly seen as a challenge as pension funds and social security budgets are forecast to run dry. But experts say this is based on the false assumption that older people have less to contribute. In fact, longevity can be very positive for society. Here are 4 ways to prepare for this new era and make the most of it...