Beginning immediately, notice every doorway you go through. Before you do, stop and see if you can get a feel for the ambience in the room you are leaving. Then step through the door and see if you can feel the change in ambience. Although it would be nice if you could describe the change exactly, at this point, you are only concerned with sensitizing yourself to finer and finer amounts of change in ambience. This exercise should be done with every doorway you go through from now until you die.
