Lateral Deltoids

I hurt this muscle on my left shoulder years ago.
It's not an easy muscle to stretch, I have to tell you. The deltoids to the front and rear are pretty simple, but not this one, because you can't take your arm inside your body, you know?
So, instead, I try to work on keeping it warm and moving. I do simple stretches just to keep my whole shoulders loose. I stand in a doorway with both hands straight out at my sides, and then step forward as if I am going through the doorway, allowing my arms to be pushed back slightly. This stretches the anterior (front) deltoid. Then I cross one arm across my chest and use the other arm to pull it slightly around my body keeping the elbow straight. This stretches the posterior (back) deltoid.

I do 5 reps of each and hold for 5 seconds each 2 times a day.
Once a week, when I am remembering to be fit, I also do lifts for my lateral deltoids. These are pretty simple. I get 16 oz cans of fruit or veggies. (That's a whole pound! Don't scoff, it's heavier than it seems! *giggle*) I hold them in my hands with my hands in towards my sides, then slowly lift my hands with my arms straight so my arms end up straight out from my body, then keep them there for 10 seconds, and slowly bring them down. 20 reps, then I'm done. This isn't exercise, remember. It's more like reminding the muscle to stay limber.
This should probably be done every day, but I'm busy, and also kind of lazy.