Inc. Magazine: 

A recent Harvard study reveals that stray thoughts and wandering minds are directly related to unhappiness. The study discovered that those with constantly wandering minds were less likely to be happy than those able to focus on the tasks at hand.

This study seems to confirm what Buddhists, sages, and saints have long taught--that an unruly mind creates unhappiness and dysfunction, and that the keys to happiness lie in mastering the mind, and not in changing external factors in our lives.

The most startling part of the discovery is that unhappiness doesn't just come from the mind wandering to unpleasant things. The study shows that people with minds that wander to neutral or even pleasant thoughts are still less happy than if the mind did not wander at all.