I like to take time to stretch out my shoulders/back in the middle of the day. I start by clasping my hands behind my lower back, then pull my hands upward and shoulders back. Then I place my left arm across the front of my shoulders to the right, place my right hand on the left shoulder and gently apply pressure to stretch it out. Repeat on the other side. Then I raise my left arm straight up, bend at the elbow and walk my fingers down the left shoulder, while using the right hand to apply pressure to the left elbow to maximize the stretch, repeat on the other side. Lastly I give myself a big hug. Hope this helps!
For shoulder and arm stretches, pull your arm across your body and gently pull outwards. By placing the opposite hand on your shoulder for stability. That way you can stand up and stretch anywhere you are.