I am not what they call a math brain. Yet not long ago I stumbled upon an equation which thrills me now as much as it did when I first blinked at it with stupid awestruck eyes. It goes like this: 7 x 365 / 60 = 42.58. As I say, thrilling. Really, it is. Here’s why: Let’s say you do an activity for seven minutes every day—and keep it up every day for a year. That’s forty-two and a half hours every year!