As the head of a leadership assessment, development, and coaching firm, I spend a lot of time with successful executives talking about their work lives — and in the past few years, many of those conversations have centered on an increasingly popular, and increasingly idealized, imagined next step: the so-called “portfolio career.” Leave behind the strain, messiness and day-in, day-out concerns of full-time corporate life for a curated and interesting medley of part-time roles — board seats, adjunct professorships, consulting roles, some lectures, some writing, maybe even a book contract —and you’ll still be in the career game, still earning money, but happier, more intellectually fulfilled, and with infinitely more flexibility… or so the thinking goes.