How do airline pilots relieve the physical stress and discomfort of sitting for long periods of time?
I was on an EMB-145. The longest flight we usually had were 3.5 hours so my experience doesn't compare to Trans Pacific routes. As a crew-member I could get up to use the restroom, but there wasn't enough room to stand on the flight deck. You learn to sit different ways (one leg under you) to makes adjustments. Then the other leg under you later and so one. Some sort of seat Yoga I guess you could call it. My strategy was to walk, walk, walk, and stay off the plane as long as I could between turns. Your body adapts to the environment after awhile regardless of your body being in great shape or not.