This financial and life-planning book wraps basic fiscal planning information around the timely mantra, "The Number" - the amount of savings you need to retire. The first 75% of the book offers retirement basics, including a selection of insights from financial planners. Throughout, it reads well, in a breezy magazine style, no surprise given author Lee Eisenberg's illustrious career at Esquire. But be patient: the richest meat of the book is near the end where he gets more specific about how much money you need to retire, and how to live both well and purposefully. The book's suggestions about how big a nest egg you must hatch to live well during retirement are mostly directed at those who are already pretty comfy. Eisenberg also offers insights on purposeful living, "a completely different way to think about the rest of your life." We find that financially savvy readers can skim the fiscal advice, while those who are unfamiliar with retirement financial planning could read it more slowly (though not as the last word on the subject). While you are pondering feathering your nest for the long term, you may want to give more attention to Eisenberg's thoughts on purpose than to his thoughts on payoffs.