Everyone has a way of zoning out. I assume.
Do you have an activity or ritual that you are familiar enough with, that it takes little to no effort to do? It eases the active mind into a comfortable resting stupor while still being somewhat awake. Tonight, I zoned out to the point of drooling. I am locked in a non-blinking comfortable stare with my old friend Photoshop.
My starting point was photo of a sewer drain and I let my mind unravel from there.