I think for many it is a reminder SHOULDERS NEED TO GO BACK AND DOWN. This will OPEN the space for the Brachial Plexus to pass under the Coracoid Process. Look at the anatomy and you can see all of this. It IS helpful to SEE what it is you are trying to do to improve the situation and reduce the compression.

Strengthen the Mid Trapezius and Rhomboids to keep the shoulders back, open the chest with chest openers (Yoga has many positions that are specially called "chest openers") and many people with TOS will get relief. Ask your PT ...he/she should be recommending the above....yes, you have to be careful that in doing various stretches that you do NOT irritate the nerve...but there is "good pain" and bad pain...after awhile you will know the difference. It's a very SLOW process but I am getting more and more relief and less flare ups and when I flare up I usually can pin point WHAT specifically I did that caused the flare up.

Watch the posture in front of the computer...watch the daily walking around posture...watch your shoulders as you bend and walk...are you concaving your chest....DON'T...remind yourself constantly.