I love doing this shorter 10 minute "Gentle Chair Yoga" at the beginning of the day. It's kinda like a pre-warm-up...
I try not to spend too much time in a chair, but I usually start the day sitting at my computer having coffee and reading news anyway etc. It helps me to have a different "attitude" while sitting...
(Here's a 20 minute version)
Developed by the therapists in the Chronic Pain Service (now called the LEAP Service) at Toronto Rehab, Rumsey Centre