After teaching posture in a seated cross-legged position in my classes, I warmed up their bodies with cat cow, and sun salutations. I mixed in plank pose where your knee touches your nose, then the same elbow as knee, and then opposite elbow to knee to warm up the core and shoulders.

AFTER heating up their bodies, we worked through these BIG shoulder openers at the end of class.

Rolling over your shoulder.

Thread the needle for the shoulders.

In both of these poses, do not push!!! Go very very slowly into the poses, and come out of the pose just as slowly. Give your body a few seconds to neutralize before doing the other side.