Abstract

Three years ago, as my fortieth birthday disappeared into the far distance in my rearview mirror, driven by a combination of vanity and fear of my own mortality and decrepitude, I committed to getting in shape.I’ve always been fairly active: I have always walked a lot, commuted by bike when that was plausible, avoided driving whenever possible, and just generally been high energy. But a childhood full of failure at team sports and a lack of innate gifts in the coordination department scared me off for decades from formal physical activity. Indeed, I was convinced that I hated working out—that I would always hate it, no matter what, and that it would always take a tremendous and ongoing act of sheer will power to do...