SJ,Hi this is Kitt.
Have you ever noticed that when we think we hear a strange noise in the attic, we hold our breath so we can "hear" better? Ever been asked a difficult question that you have to answer immediately and notice that you're holding your breath while you think? I can think of a few other times I do this and I have no idea why. Come to think of it, maybe I am the only one who does it......now that is spooky, but my gut feeling is that almost everyone does this to some extent or another.
That you hold your breath is not bad, in and of itself, but the fact it is causing you to feel anxious is not good. When we hold our breath, we're throwing our oxygen saturation levels off and this can create feelings of anxiety, even panic. Just as hyperventalating (taking short and shallow breaths) will throw our carbon dioxide levels out of whack and make us feel lightheaded and "weird," holding your breath no doubt causes some of those same feelings.
Perhaps as was suggested, just become very aware of your breathing, but not obsessed, and when you notice you're holding your breath, let it out and take a few really deep "cleansing" breaths. I think if you are vigilant about this and practice, you will be able to overcome this "habit."
There are a great many books out there on breathing since we apparently all do it wrong - lol. Keep track, if you can, of what happened, what you were thinking or feeling, just before you held your breath. That could possibly give you a clue as to what is causing you to do this. Personally I think it's just a nervous habit you've gotten yourself into and have held onto for a very long time. With work on your part, you'll be able to break this pattern.
If it is really interfering with your life, then obviously see your doctor to rule out a physical cause. Since this is enough of a concern for you that you've written in the Anxiety Forum for answers, my thoughts are that this "habit" could indeed be inducing panic for you.
Try some self-help things first and if you get no relief, speak with your doctor........but I think you can beat this on your own. I believe in you.
Remember you are never alone here in the forum. We know where your coming from and what your going through.
Peace,
Kitt