Never, ever, recline your airplane seat. Sit up straight, with your weight on your spine like a human being. Even when sleeping. When you lean back and try t

Never, ever, recline your airplane seat. Sit up straight, with your weight on your spine like a human being. Even when sleeping. When you lean back and try to get "comfortable", you force all of your weight sideways onto your butt, which now has to act as a scootch-guard to keep you on the seat at all. That works for a couple hours max, after which you're in agony for the rest of your 12 hour flight. Learning to sit on chairs is a good skill in general. Getting an office chair that doesn't recline will do wonders for your health as well.