Absolutely know how you are feeling. This is my most aggrevating symptom. I used to run five miles a day. Then one day in February 2003 I felt like I could not expand out. Basically I could breath to a certain extent and then my diaphragm and muscles making my lungs work would just not cooperate. I have to make a conscious effort to take deep breaths. I have had all the tests, they are normal too. I am attorney and a young woman, therefore they blame it all on stress. Of course there is a reason that I cannot walk up to the top of Beacon Hill (where I live) (Sorry but GO SOX!) or run or walk up a flight of stairs without shortness of breath, and believe me I am not anxious everytime I do these things.