Who knew you could work your obliques on an airplane? Start by making fists and bringing them in front of your chest like you're holding dumbbells near your shoulders. Sit up straight and twist to the left while exhaling. Come back to center and inhale. Twist to the right and exhale. Come back to center and repeat. Make sure you turn in a controlled motion and keep your elbows by your side and your hands next to your chest as you don't want to be swinging into your neighboring passengers. It also gives you better muscle control. Do a couple sets of 15.