Never underestimate the power of a good book. When did you last have so much time on your hands, just to read? Don't worry about anything else for a while, and sit back and get lost in a novel. You may just find you haven't had this much fun in ages.
Before boarding the train, do a little research on the countryside you'll be traveling through and create a list, a checklist, actually, of things to be on the lookout for. A barn of a certain color, a type of hat, a particular animal---anything at all. Make the list significant; at least 10 things. Really ambitious types should go for 50. As the scenery whips by, or when the train idles in various stations, keep an eye out for those items on the list. Enjoy a special reward after successfully finding all the things on the list.
Buy 20 postcards and the stamps to go with them at the station. Bring along your address book, too. As the long hours go by, write to 20 people whom you haven't spoken for a while and get reacquainted. These can be family members, friends or old acquaintances. Describe the trip, the scenery that is passing and anything else on your mind. At the next station, drop the postcards into the mail.