Chairs have become the biggest rival to pain free movement: hips shorten, glutes deactivate, hamstrings press together, back begins to round, core disengages, and head sits forward. It's no wonder we often experience back pain, shoulder pain, hip pain, and carpal tunnel agony after sitting on a plane, in a car, or at a desk at work. As hard as we may try, we can't avoid sitting. So, how can we fix this? Enter the 20-minute rule...