A few months ago I got a new job that required me to commute for two hours each day. I tried doing many different productive things while sitting on the bus (the means of transportation I used), including reading, listening to audiobooks, watching videos, and even meditating. Eventually, however, I reached the conclusion that doing Anki reviews (using the AnkiDroid app) was, by a wide margin, superior to all these other activities. If you own a smartphone, you might want to give it a try. (And if you don't own a smartphone, you might want to consider obtaining one.)