Power
You have power—all right—the power to heal. You help people with just the touch of your hands...and with your medically informed and rigorously documented exercise programs. In the physiologist/patient dynamic, there's no doubt you're the top dog.
But in the health care system as a whole, you're relatively low on the totem poll. While "low" can be a good thing—like in relation to your blood pressure—that's not the case here. Unless you're lucky enough to score a director or manager position, you're taking directions from someone else and the pay isn't always great enough to justify it.