Stand with your heels, rear, shoulder blades, and back of your head against a wall. Put your elbows and forearms against the wall with your hands at your eye level (like you're making a "W" with your arms). Slide your arms up (to make the "Y" of "YMCA") and then back down to the starting position.
If your lower back hurts, step your heels out from the wall a couple inches, leaving your rear, shoulder blades, and head against the wall.
Forearms don't touch the wall? Keep pressing them back towards the wall anyhow.
It should BURN right between your shoulder blades.
DO THIS EVERYDAY!
You probably need this, too:
Please hold these longer than this nice young man does, but
DO IT EVERYDAY!