Thinking in microlives also makes it evident that unhealthy, life-shortening choices can be balanced by life-extending ones: the first 20 minutes of exercise each day, for example, adds two.

Averaged over a lifetime, the following habits are linked to the loss of one microlife: smoking two cigarettes, eating a burger, being roughly 11 pounds overweight, chugging a second or third alcoholic beverage, and watching two hours of television.

I suggest a simple way of communicating the impact of a lifestyle or environmental risk factor, based on the associated daily pro rata effect on expected length of life. A daily loss or gain of 30 minutes can be termed a microlife, because 1 000 000 half hours (57 years) roughly corresponds to a lifetime of adult exposure.