My doctor actually gave me some exercises recently which I thought were interesting because I had never heard of them before.
First, you stand an arm's length away from the door and then extend your hand and fingers so that they touch the edge of the wood paneling.
Then you very slowly walk your fingers up the wall as though they were a little spider climbing up at a very slow pace.
Once your fingers are as high as you can raise them, you switch hands and walk your other one up the wall.
Supposedly, this will teach you to stand up straight and keep a flatter back so that you do not hurt your shoulders when you are working in the restaurant industry, or similar field.