Who didn’t love that great film, Snakes on a Plane: great plot, well acted, well paced  and utterly believable.
In that great tradition, can I present, “Necks on a plan”

Air travel presents a great opportunity for you to abuse your body and create long lasting pain. Probably not quite as effective as  buying the services of a Mayfair dominatrix, but  still, pretty good.
To really make your neck hurt, let it drift forward and down as you stoop to read: if you can switch your abs off too and “hang” for 1, 2, 3 , 4 hours, you will really over stress those upper back and neck muscles and develop some really great pain. For free ( excluding the cost of the flight,  of course).
If, however you don’t want the rest of your week blighted by  agonising neck pain, why not , gently,  engage your abdominal muscles ( “tone” rather than tension) and rest  the back of your head on the head rest. The clue is in the name. HEAD REST: something on which to rest your head!
DOAH!!!! I hate to say, it. Your mother was right!. Don’t slouch, and sit up
So, necks have  a lot to do with the upper body and shoulder mobility ( and lack of it). Why not come to one of our amazing “shoulder mobility” masterclasses