How much of our lives do we regard as items on our to-do list? We often speak of obligations, responsibilities, duty—all the things we have to take care of before we can allow ourselves to work on what we want to. But the truth is, as the cliché goes, the only things we have to do are die and pay taxes (and judging by the loophole-riddled tax returns of high-profile billionaires and government officials, the latter is apparently optional too). Most things in our lives are things we choose ...