When I lived in NY I used to carry a small sketchbook and drew during my commute. I had to move fast because the subway is crowded and always moving, so many of the drawings were done in a minute
or less. But in doing them it got me to experiment and think about the marks I was putting down on paper. It also helped make the ride go faster and was a great way to start off the day
(productive). Above is a selection of those drawings.