|This is a picture from the internet, but the booth at the show looked identical to this, minus the plasma globe and company id.|
It was an interesting experience, sitting with a strap over my ears and the tube ends up my nose, getting a dose of concentrated oxygen. I thought the slightly scented oxygen hit would wake me up, helping me get through the rest of the day. In actuality it made me kind of tired.
So why mention it here? First, it felt like a very sci-fi thing to do, sitting on a stool and getting a 'hit' of pure oxygen. Second, it struck me that health fads are a huge part of modern day life and yet I don't remember reading a book - science fiction or fantasy - where a current fad is sweeping through. (I will note here that not remembering one isn't the same as there not being one, I've never considered this before so it I've encountered a health fad in a book I've probably skimmed over it.) And fads are universal. Sure, the object of the fad will be different in different places, but fads can found everywhere, in every time, whether for food items, healing baths, clothing, cleanliness (a scented pomander ball anyone?), what have you.
That's not to say fads should be front and center of books, but mentioning one - and how the characters react to them (followers, sceptics) - could help make your world feel more real.