While Dave's answer may provide a partial answer to your question, there are other factors as well. You say your lung function is 62%, which, quite frankly, many of us would be delighted to have. Many of us are at much lower levels. You should look at the PFT results to see what your DLCO is. That number tells you how efficiently the alveoli are exchanging CO2 for O2. This fits into to Dave's explanation, but it's not just shallow breathing that could be the problem; if the DLCO number is low, that may be part of the problem. I would suggest that you go to this site and look at all the videos in the COPD 101 series. The fourth one is the one that gives a great explanation of how the lungs work and why we get short of breath.

http://www.copdfoundation.org/Learn-More/For-Pa...

I would really encourage you to learn good breathing techniques, which are part of the video series, and practice them until they are second nature and you do them all the time.

My final recommendation is that you talk with your doc about beginning a daily aerobic exercise program. 30 minutes of aerobic exercise on a daily basis will force you to breath deeply and will help you make that 62% lung function you have as efficient as possible. Once you have the aerobic part down pat, you should also begin strengthening exercises for upper, lower and core muscle groups. The fitter you are, the less O2 you will require for ordinary tasks and the easier your breathing will become.

Running out of breath/shortness of air, if you are doing nothing, just sitting around, relaxing, and you develope shortness of breath, like you you can't get enough air in, that would tell me, that you are possibly breathing with short little breaths, and you may not be aware that you are doing it. Most don't reallize they are, this my friend is called shallow breathing. When you shallow breath, which is common when you sleep, you are not pushing all that bad air out of your lungs. That makes it impossible to beath in enough good air. So then you begin good breathing excercises, that excercise of good breathing, is by using your stomach muscles, push out all that bad air out of you lungs, then breath in good oxygen, filling your lungs up, causing your stomach to fill up and buldge out, do not try to only fill your lungs up, by only filling up your chest...that will cause shortness of breath too. So anytime you are awake, practice, practice, practice, good healthy breathing. What will that do for you, is prevent shortness of breath, strengthen your stomach muscles, which helps for good lung functioning, and when you continuously practice this good healthing breathing excercise, it will help you to breath better when you are sleeping, because you are training your body to breath correctly....like when you were a child. Ever watch a baby breath, especially when crying, they use thier stomach for getting in enough good air, and for pushing all the bad air out. But as we age, sometime after 30 years of age, we begin to train our bodies to start breathing shallow, thus we start running out of air when we walk faster, or exert our selves, by lifting something heavy. We start thinking there's something wrong with our lungs, usually, there's nothing wrong with for say your lungs, but it's that shallow breathing syndrome, we trained our bodies to do ! Also, is you are sitting down and eating to much, at each meal, you will experience shortness of breath. Because you are not leaving enough room in your abdamon, for enough air !! Also, depriving your body of enough water, can cause shortness of breath. So my friend, i hope this helps you out, to understand, some of the causes of shortness of breath. I will pray also for you. God Bless you, breath well !

The breathing exercises do help and so does exercise that gets you to breath deeper and I have found yoga is very good for me. I goes twice a week for an hour and it has helped my breathing a lot. In Yoga you have to concentrate on how you breathe and that makes you more aware.

Running out of breath/shortness of air, if you are doing nothing, just sitting around, relaxing, and you develope shortness of breath, like you you can't get enough air in, that would tell me, that you are possibly breathing with short little breaths, and you may not be aware that you are doing it. Most don't reallize they are, this my friend is called shallow breathing. When you shallow breath, which is common when you sleep, you are not pushing all that bad air out of your lungs. That makes it impossible to beath in enough good air. So then you begin good breathing excercises, that excercise of good breathing, is by using your stomach muscles, push out all that bad air out of you lungs, then breath in good oxygen, filling your lungs up, causing your stomach to fill up and buldge out, do not try to only fill your lungs up, by only filling up your chest...that will cause shortness of breath too. So anytime you are awake, practice, practice, practice, good healthy breathing. What will that do for you, is prevent shortness of breath, strengthen your stomach muscles, which helps for good lung functioning, and when you continuously practice this good healthing breathing excercise, it will help you to breath better when you are sleeping, because you are training your body to breath correctly....like when you were a child. Ever watch a baby breath, especially when crying, they use thier stomach for getting in enough good air, and for pushing all the bad air out. But as we age, sometime after 30 years of age, we begin to train our bodies to start breathing shallow, thus we start running out of air when we walk faster, or exert our selves, by lifting something heavy. We start thinking there's something wrong with our lungs, usually, there's nothing wrong with for say your lungs, but it's that shallow breathing syndrome, we trained our bodies to do ! Also, is you are sitting down and eating to much, at each meal, you will experience shortness of breath. Because you are not leaving enough room in your abdamon, for enough air !! Also, depriving your body of enough water, can cause shortness of breath. So my friend, i hope this helps you out, to understand, some of the causes of shortness of breath. I will pray also for you. God Bless you, breath well !

Sorry it has taken me so long to answer your question. I slowly learning my way around the site. Great Question by the way. Did you know that the maximum amount of air your lungs can hold—your total lung capacity—is about 6 liters? That is about three large soda bottles.

Your lungs mature by the time you are about 20-25 years old. After about the age of 35, it is normal for your lung function to decline gradually as you age. This can make breathing slightly more difficult as you get older. If you notice any sudden difficulties in breathing or shortness of breath, talk to your doctor right away. This could be a sign of lung disease and not the normal process of aging.