Holding my breath

I don't breath appropriately. Most of the time i hold my breath its like I'm tensed. When i was a child i started doing this when i was near people but today (40 years old) i hold my breath all the time even when i walk. When i am sleeping i breath appropriately. I have developed a lot of problems like Photophobia and Phonophobia . Is there any exercise that can make me breath appropriately?