I've focused to this point on thought as the characteristic that differentiated us from other animals. But thought only helps us get where we want to go. What makes us want to go there?
Our motivations come from our emotions. Emotions form the long-term psychological context for our lives. Where thoughts flit through our mind, our emotions persist. Typically, we have predominant states that may persist for many months, with episodes of other emotions that may last from minutes to days. Compare this to the evanescence of thoughts, which last only a few seconds.
Emotions are hidden, sometimes frightening things. They arise from deep within our brain, along neural pathways that were hard-coded over millions of years to facilitate our survival and the survival of the species. Fear, lust, greed, vanity and envy. You know the lot. The drive us to be separate, to dominate and to control. And on the other hand, courage, love, compassion, humility and pride. They drive us to join, to sustain others and to sacrifice for the common good. The survival of a new-born infant depends upon them.
Emotions are dangerous when they drive us into magical thinking. Our strongest emotions occur in the course of imagining, particularly when the subject of our attention involves great psychological loss or gain. We focus on the end results - achieving the goal, or avoiding the loss - and go "tilting at windmills". The end result can be a disastrous squandering of resources that would be better focused on more realistic means for improving our lives and our selves.
Unfortunately, our media-driven society tends to emphasize this predilection. In any large society, events occur daily that happen only once or twice in most lives. Presented with a common diet of "true-life" stories that manifest our wildest hopes and fears, the moderate diet of rationality most of us live on can be worn away.