A flight of 7-8 hours or even more than 10 can only be long, long and boring, or, in the happiest case, a flower in the ear. It all depends on how you want it to be and how you act in this regard.
One of the most productive things you can do is, of course, read if you are a fan of this activity. Surely you have a bulky book in the library, which is always hard for you to take on the subway, tram or bus, when you have to commute for at least half an hour. In such a situation try to make room for them in hand luggage. You will definitely not read for hours without pausing, but you may end up giving it to someone as a gift when you get to your destination, because you will already know everything, down to the last word.
Movies, books, games
If you are also thinking about fun and making time fly as fast as possible, you can purchase a few mini travel games in advance. Nowadays there are a lot of mini versions of some famous games, adapted for flights.
Maybe there will come a time when some companies will offer the opportunity to rent them, but in normal size. Several airlines actually had their heyday in this area of entertainment, sometime in the 1980s and 1990s, when an experiment was made with slot machines.
right View From The Wing - the leading online source for travelers interested in finding out about the best travel deals - Singapore Airlines tried slots for two months in 1981. It introduced them on the route from Singapore to San Francisco. Also in 1990, Swissair launched the trend of slots attached to seats. Those interested could choose places with mini-slots, having adrenaline during the flights.
The results of this experiment were not as satisfactory as the feedback received after the same experience at airports, so this option no longer exists. Even so, if you really want to have access to this type of game, while you are in the air and you are also willing to opt for the wifi fee, you can enjoy various online slots, holding the laptop on the table attached to the front seat. Add a pair of headphones to fully enter this universe and surely those around you will notice how well you manage to spend your time in a long flight, without saying that you get bored for even a minute.
Movies with and about aviation
If you are a cinephile, before the mentioned options it will occur to you that you could very well watch two or three movies with and about aviation. It all depends on the duration of the flight and the movies. It would be interesting and captivating to choose a series, one that has become legendary and about which you have heard many conversations. Maybe you've never seen some old movies, with famous actors, about which you don't know much.
You certainly know who Elizabeth Taylor is, the famous purple-eyed actress and her 3-hour film about Cleopatra, which was the beginning of her relationship with Richard Burton. You would also have the version of the films directed by Béla Tarr, the Hungarian filmmaker widely considered one of the most important authors of world cinema. His longest film is Satántango, with a duration of 7 hours and 19 minutes and with action that takes place in a village in Hungary, in the 1990s.
Business activities
With a laptop and an internet connection, you can also set aside entertainment and recover from your duties at work. When you run an online business, a long-haul flight is actually the perfect excuse to deal with it. You can use your free time to recover from the work you have been postponing. In most long-haul aircraft there are sources of electricity, so that the laptop always has "fuel".
Nobody says you should get involved in one activity without even taking a break. You may as well choose simultaneous activities. Maybe it wouldn't seem at all strange to apply a mask on your face while watching a movie or to serve a snack while rolling the dice. Nothing is out of the ordinary as long as you don't think about borders, while, paradoxically, you cross borders in the air.