In 'From Strength to Strength,' Arthur C. Brooks offers a powerful metaphor for midlife transformation: the Aspen grove, nature's blueprint for life's second half.

The most profound economic and cultural shift of our time isn't happening in Silicon Valley's tech campuses or on Wall Street's trading floors. It's happening in the minds and lives of people we've traditionally called "middle-aged" – a term that has become as outdated as the rotary telephone.