It is as if, by constantly attending to and fervently thinking about a particular problem, we are not allowing a part of our minds to access the very information that we may need to "solve" the problem. This seems to be the very mechanism that allows for mental clarity after certain repetitive, if not meditative activities, like running, folding laundry, gardening, taking a walk, etc. It is as if such mundane activities require just enough mental energy to negate the obsessive, ruminative quality of our thinking, thus giving way to the flowing, creative energy of the unconscious processes of our wiser selves.
http://www.newyorker.com/online/blogs/frontal-cortex/2012/06/the-virtues-of-daydreaming.html?mobify=0%2F