Breathing is something that each of us takes for granted. We do it all day long and think nothing of it. The only time we would really notice the fact that we breathe all day is if we stop..and then we notice.
If you do pay attention to your breathing, you will find that when you are concentrating on anything we tend to hold our breath.
It would benefit you to take a few moments, preferably every hour (if you can), to stop what you are doing and breathe. I mean breathe from your diaphragm. Deep. Let your stomach fill with air, like a balloon and slowly let it out. Repeat a couple more times and then proceed to whatever you were doing. You will find that you will be able to focus more and do a better job at what you are doing.
(See 7 Count Breathing Exercise on another page)