I do these:  could not paste the pictures.

1) Sit on feet and stretch you hand straight , move all the way left very gently and stretch straight then go right gently inch by inch moving your fingers.

2: sleep on you back , bring your left leg over to right side ( every time you have to do it very gently: if you jerk it may have negative impact) , do it other side.  

3: sleep on you back : bring your right knee to your chest, then left 

4: sleep on our face and pull your head all the way up.

There are many but start these from today. 

you need to sit straight on office chair, do no slouch.