Have you viewed sitting as a position of Chronic Stress?
If not - you should - Why? Well - think of how many hours a day you spend sitting.
It is probably more than you think - Especially if you work a desk job or spend time watching TV, movies or playing Video games. The time spent sitting can go into the hours of time during a day. Individuals who work at a desk and/or computer can spend 4-8 hours a day seated and then go home and sit more.
If we break it down - we hopefully spend 8 hours sleeping - and if we spend 8 hours at work seated - that only leaves 8 hours to fiddle with - and how do we spend that? I will be generous and say that one hour of that 8 is spent exercising - 7 left. TV - 2+ hours on average - 5 left. Driving - lets just say 1 hour (although commuting can extend this greatly - plug in your own number) - 4 left. Meals - three meals - lets say 3 hours total (your time may vary) - 1 hour left. We will chalk that one hour up to various walking and moving around.
Total time seated and inactive = 22 hours. Total time moving and exercising = 2 hours!
This is of course a gross generalization that is meant to emphasize the point of how much sitting we do during a "typical" day it doesn't reflect everyone's actual time seated - but chart out your day and run the numbers - it may just surprise you.
How is all this time seated bad for you? High levels of pressure within the discs to begin with - sitting removes the shock absorbers of the legs and muscles that help us deal with gravity - we sit directly on our pelvis (ishial tuberosities to be specific) and the weight and gravity is sent directly into the spine. And this is if ideal alignment is maintained - forces increase greatly if you round the back or slouch while you sit. Tightens the hip flexors and hamstrings - sitting places both in a shortened position - not good. If the upper back rounds we cannot breath with our diaphragm - and we end up with shallow chest breathing - lower oxygen levels and poor thoracic mobility. Plus we are inactive - no movement = poor lymphatic drainage, increased heart stress as it pumps without the aide of muscular contraction to move blood better, reduced caloric burn etc...
Getting the idea?
What to do about it? For every 30 minutes seated - Stand and move for 5 minutes. Perform standing extensions, squats, easy shadow boxing/shaking drills, and walk for 5 minutes. Joint mobility drills fit in well here. As does Pavel's Grease the Groove program - click through my website product page for the Naked Warrior for details.