I am 70 years old and was diagnosed about 12 years ago with Emphysema - COPD. It was controlled with Advair, Spireva and a rescue inhaler until two years ago. I started to see a gradual decline in how I was doing. Just recently I have been diagnosed as severe COPD. Oxygen was prescribed for using with exercise and activities. I am not sure how long it takes to tell a difference in how I feel, but after two weeks, I do not feel any different. I keep ready how much better everyone feels after using oxygen. I also see some post they use it at night only. I asked my doctor about it and he said the body does not store oxygen so that was the end of that. I am ok at rest, but just doing the simplest things will make me SOB. I work 35 hours a week at a desk job. I do try to get two 10 min walks a day at my office using oxygen now and that does making walking easier. I have to make myself do that. I have no energy and I feel like every bone in my body aches. Maybe due to lack of oxygen? Good luck to all of you with this dreaded disease. I work in the billing office for a pain clinics and I am grateful I am not in pain and do not have to take the drugs they have to take. So things could be worse.