John Tierney writes about daydreaming, zoning out, and various other kinds of mental wandering:

In the past, daydreaming was often considered a failure of mental discipline, or worse. Freud labeled it infantile and neurotic. Psychology textbooks warned it could lead to psychosis. Neuroscientists complained that the rogue bursts of activity on brain scans kept interfering with their studies of more important mental functions.

But now that researchers have been analyzing those stray thoughts, they’ve found daydreaming to be remarkably common — and often quite useful. A wandering mind can protect you from immediate perils and keep you on course toward long-term goals. Sometimes daydreaming is counterproductive, but sometimes it fosters creativity and helps you solve problems.

What strikes me in the article is how many different ways our minds wander: there's "mind wandering," which happens "when you’re trying to accomplish one thing and lapse into 'task-unrelated thoughts,'" and happens during about 30 percent of the day (wow!); "mindless reading," where your eyes are moving across the page but you're not really taking in the words; and "zoning out," where your mind wanders away from a task or place, and you don't even notice.

If your brain normally wanders away from the here and now for several hours during the day, no wonder workshops and facilitation are a challenge. Staying focused requires a substantial amount of energy.