I wonder if these small cans of oxygen, on sale on the internet are of any use in boosting energy. I have arterial fibrillation, but can still walk a couple of miles, but do not like hills. I lead nature walks here in the UK, but 2 or 3 miles is my limit. I am tired of felling tired although have to accept that I am getting older. These oxygen boosters may be of use, maybe they do nothing really, and wonder if anything else could boost my energy levels. Thank you.