This year, we’ll be donning birthday hats for more people turning 65 in the US than at any other time in history, in what the AARP is calling the “silver tsunami.” And the nearly 4.1 million seniors celebrating this milestone are doing things a bit differently than their parents were at the same age. “I’m not winding down,” Robin Darrow, a VP of sales and marketing who will turn 65 this year, tells the Wall Street Journal. “I’m just starting.” She’s far from alone. Here’s what makes these younger boomers different as they reach their mid-sixties. Retirement? What retirement? Like Darrow, many …