From time to time to do the most simple exercises: tense and relax your hands and feet, rotate the head, feet apart, move your socks on myself and on my own. It stimulates blood circulation and help you avoid unpleasant feelings when flowing muscles.
Once a half to two hours to get out of the place, a little walk around the cabin (try, of course, choose a time when you do not create their walk inconvenience other passengers or flight attendants).
If your neighbor is not averse to traveling companion to keep the conversation - talk to him, just about any topic. Maybe you can find some common interests and hobbies. The conversation time flies.
When you will be served lunch, try to concentrate on the food, do not think about anything extraneous. If it tastes good - try to tell myself: "Well, here, the flight takes just fine and comfortable aircraft, and such a good dinner." If the food is very average quality, comforted thought: "Well, what can we do, it's just a plane, rather than home cooking, especially not a restaurant." Eating will take a minimum half an hour, maybe more.
Take in the cabin book, preferably a light character. Flight - not the best place to read a serious philosophical work, for example. But some ironic detective or adventure novel will come in handy. You can also read a newspaper, crossword puzzles, for example.
If you do not like to read in flight or it has fallen to a later time - you can listen to the player (of course, using the headphones), watch a movie on the laptop screen. Monitor light is sufficient for these purposes.
A good way to escape from boredom and impatient irritation in flight: Remind yourself that any other way trip would take many times longer!