Christian R.,
Your observations are quite accurate. Most of our daily thoughts, as well as those during meditation, are random and useless. Eckhart Tolle discusses this from a slightly different point of view in his excellent book,
A New Earth, which was recommended here at
http://www.network54.com/Forum/254541/message/1208494774/Free+online+sessions+with+Eckhart+Tolle+and+Oprah+Winfrey by Gavin H.
The specific thoughts we have during meditation are associated with stress release. But their connection is like dreams: sometimes we can understand the meaning of a dream and sometimes we can't. Similarly, sometimes we can understand the stressor represented by a thought (such as when we recall a traumatic accident) and sometimes we can't (such as when we wonder how many toothpicks are in a box).
But no matter what thoughts or other experiences come to us during meditation,
we never concentrate on the mantra. Concentration interferes with transcending. It can even cause stress. It is the opposite of what we want to do. We want to be innocent, spontaneous, and natural. We start the mantra as described in the NSR manual, then let it go. We never concentrate. If our mind is filled with other thoughts, that is fine. That shows that we are releasing stress. It doesn't matter that they are sometimes the exact same trivial thoughts that we have during the day.
It doesn't matter.
After a few months or years of regular practice of NSR Meditation, many of those older and deeper stresses start loosening up and dissolving. Then we have fewer random trivial thoughts. Our mind becomes clearer and capable of natural, intelligent focus on a single meaningful idea or goal. This is the basis of "do less and accomplish more", the basis of high productivity and accomplishment in life.
David Spector
NSR Meditation/USA