It isn't just the Old Guard. The outfit where my wife works has an average age of 28, and they have to make the point that you don't come in when your sick. In the software business, it's even less sane than it is in most, because you can usefully work from home if you have the energy.

When you're self-employed, it is trickier; but is it more responsible to let people know that if you did show up, you could render the entire staff less than useful, or to just show up and give them all the creeping crud? I suspect it depends on the individual clinic in your case.