One of the hardest things for me to do is...nothing. I'm not a sitter. I don't idly pass life away doing nothing. As an exercise in "being" (which also means DOING NOTHING) I've been doodling for no particular reason. Just to doodle.
Flower doodles. Micron pens on a previously painted page (watercolors) in my mini art journal (3-1/2x5).
Paisley shapes: micron pens in multiple colors.
Unwinding at the end of the day doing a page of mindless doodles is unexpectedly relaxing. No stress. No need to "produce" something profound or "artistic." Just doodling for the fun of it.