Welcome to Flyertalk!

This may or may not apply to flights you might be taking but for the future, you could try out certain carriers that have places to walk to in the cabin such as bars, lounges, etc. This relieves the monotony of having to be confined to your seat for many hours and gives you a chance to stand, stretch and walk around. Not very many carriers offer this amenity and if they do, it is generally offered in first class or business class.