I love taking a walk and listening to music because it frees my mind. Sometimes my concentration goes directly to the music, and then it bounces around from foreground to background, from thematic material, to lyrics (if there are lyrics), to structure, to sound, to sound production, and to various other musical associations, like the relationship of the piece at hand to something I listened to at another time. Sometimes the music becomes background to my thoughts, while I fly off on tangents, follow various lines of thought, plan, fantasize, observe, and react to the world around me. (Somehow when I listen to Mozart I tend to become acutely aware of things like the shapes and states of leaves and flowers.)
And then I bounce back into what is happening in the music.
It is an inner world devoid of external responsibility: I know the parameters of my walk, and can think what I want in the time I have. The rhythmic physical movement of my walk is rarely in time with the music. It is as if the life of my body and the life of my mind are separate entities that coexist for the hour I spend on my walk (as opposed to the time I spend practicing, where the mind and body are constantly interacting in both conscious and unconscious ways).
When I am listening to something that I am going to review, I have to listen critically. The habit of free association that I have developed on these walks allows me to be honest in my assessment of the recordings I review, translating the fear of not having something worthwhile to say, into a free-flowing safety zone, where all thoughts are acceptable, and all thoughts are equal.
But listening without having to write a review is kind of like a vacation.