There are two different breathing techniques you can use to help get more air. They will even help you to relax when you start to tense up, especially when you are starting to have trouble breathing. You should talk to your doctor before trying these breathing techniques, to see if they are right for you.
It can be a vicious cycle when you start to have a hard time breathing. It can cause you to feel anxious, which only makes it worse. Also, you'll avoid activities that make your feel breathless, which can be as simple as walking slowly around the house.