It has only been since the Baby Boomer generation began to cross the retirement threshold that we’ve had to seriously confront the new challenge of our longevity. Although most of us are now bracing for the probability of living 20 to 30 years in retirement (nearly double the retirement life spans of our grandparents), what isn’t quite as clear is that our actual longevity is a moving target. That is, the older we get, our life expectancy increases, and that can have serious implications for the way we plan for our retirement income.