Leave it to the boomer generation to reinvent one more thing. As children, they reinvented the housing market: Their parents moved to the suburbs, leaving the city for safer neighborhoods and homes with enough space to give each child his or her own bedroom. Boomer girls now had the privacy to talk on their Princess phones and boomer boys the ideal space to play with their Hot Wheels. As young adults, boomers reinvented the shopping experience. The first enclosed shopping mall opened the year the oldest boomer turned 10, an age when children become independent shoppers. Their generational love affair with Spencer Gifts and Orange Julius began. Now in their mid-40s to 60s, boomers yet again have reinvented an American institution: the midlife crisis. Yep, we all remember someone who bought a red Porsche or a blue Corvette. We’ve seen a colleague buy a timeshare in some grand vacation spot, and we’ve a seen friend pick up a new hobby, like sky diving. Each of these...