Compression socks are a must for me regardless of the duration of my flight. These keep my legs feeling fresh and energetic and reduce any swelling that I might incur on my flight. I bring a lot of my own food as airport food and airplane food is loaded with salt and a multitude of additives causing inflammation which can affect your legs and bowels.
I buy a liter of water for a long-haul flight plus bring my own stainless steel water bottle and fill it before the flight. Most airports now have filtered water stations for filling your own bottles. (This helps reduce the use of plastics too!) Drink as much water as you can on the flight and avoid alcohol. This will keep you hydrated and make you get up and go to the bathroom which is what you want to do while on a flight. MOVE and STRETCH.
Again, hydration is a key as it will cause you to stop and get out of your car to relieve yourself as well as give your body a chance to walk and stretch. Making sure your seat is set at the proper height and depth is extremely important as well as engaging your lumbar support if that’s available to you.
Getting adjusted before and after your trips can help deter some of challenges of travel, make it pain free and allow you to enjoy your trip instead of suffering from neck and back discomfort and putting a damper on your holiday.