What strength/mobility related are you doing in your everyday life?
I mean something simple like having your grocery back and holding it in different shoulder angles and such.
Good stretches you can incorporate to sitting, watching TV or somewhere else?
One I like to do is when traveling with bus, I stand with my feet together and grab a bar with straight arm(s) and try to hold to the position with the bus accelerating, turning, whatever. Point is to try to balance with your feet as little as possible and tighten the core. Can get some pretty intense shoulder training done.