To me, relaxing is tranquility. Relaxing is about staying unoccupied in one place or position for a period of time, thinking of nothing and just enjoy life.
To me, relaxing is about letting the mind wander to a peaceful place and allowing the peaceful place to stay. I often like to let my mind wander to a place of water. It always calms me whenever I hear the sound of naturally running water.
To me, relaxing is about finding my calm. What quiets your mind when you are feeling overwhelmed?
Finally, to me, relaxing is all about the quiet. No traffic noises, no sirens, no planes, no one talking, just me, my thoughts, and imagination.