I have this situation going on also. I was told early on that RSD is a 'Use it or Lose it' affliction, which as has been said, is a double edged sword.
You (We) need to move! Start by walking, at least around a block, and build up to more! Start at whatever level doesn't hurt too much, and build up from there. If you can get to a gym, or a warm pool that's the best! But, Don't just sit and watch tv, or be at the computer. You've got to use it!
As I said, I'm in the same situation after 27 yrs of this, (with TOS).
The weather is so awful, it's impossible but, sometimes, getting out and walking can do a lot for your mood / depression too!
(I'm not suggesting a walk to the bar) Hah!

But, I hope you can move around. A walk around the block will get your blood circulating, your lungs working, and will help with chores like doing the wash, vacuming etc.

Be Well!

p