On not having any choice on thoughts that spring up

One hears, one does not seek; one takes, one does not ask who gives; a thought flashes up like lightning, with necessity, unfalteringly formed —I have never had any choice.
This is Nietzsche, and not having any choice might be termed cognitive dissonance but what of cognitive discipline of say concentrating a minute at a time on the real world what is around you  trees sky pavements etc