I was reminded of that this week when dealing with someone who had turned a possibility into a vivid inevitability. This person's emotional state was no different than if this event were really happening. In the world of actual events, it was a remote possibility.
It's worth remembering when our minds latch onto certain possibilities, when we consider what might happen. We can let the pleasant feeling of a daydream substitute for the the actual event, a fantasy become a substitute for reality, fear or hope becoming proof.
I think one of the harder things in life is sustaining emotional tension, the sort of unresolved feeling that leads you to action for sustained periods of time. It's much easier to lapse into hopelessness or daydreams than grind it out over long periods of time.