Interesting thoughts. I can tell you that, for awhile now, I've almost assiduously avoided the term 'health' as something that, as a fitness trainer, I'm all about. Really, I'm not about health at all, or at least using the term ... because it's just so downright squishy a term.
In fact, I make a point of reminding my audience that we're all going to die.
Nowadays I just talk up "how you look and move", two things that are relatively easy to quantify and change (which may indeed positively impact ... uh-oh, I'm going to say it - 'health').
Actually, I'm more prone to use the term 'health markers.' That much is true. But it still doesn't with any degree of certainty buy one another day.