I have a 40 minute commute (each way) that is mostly a train ride. When I first started with this commute I was very worried about wasting that much time every day, so I brought lots of printed material with me and would try to study on the train. Now that I've been doing it for 3 years I've completely abandoned that - I just use the commute as a mental break. After a hard day of work ~40 minutes of daydreaming is just what the doctor ordered before making the most of my evening.