As a manual therapist/chiropractor people come to see me for such a variance of issues that it hard to pinpoint any issue that you see more then another. The bottom line is they are usually in pain or aren't able to perform an activity to the level they desire.
I believe being a strength and conditioning coach is a great lens to view these patients/athletes in. Strong covers up a multitude of sins. Not all of them, but a lot of them. Strength will improve mobility issues. It will improve overuse injuries.
So every patient and athlete I treat is being viewed from these two lenses. Therapy and Strength and Conditioning.
The problem then lies in the tricky navigation of being only their therapist and not their strength coach.
How much information should be given? How much advice should be offered? How blunt?
This can be a tough pill to swallow at times and you as the therapist will risk losing the patient I believe, but at the end of the day, if what you believe isn't being stated, you risk more.
If you have a patient with flexion intolerant lower back pain and they love their bootcamp with crunches, sit ups, a squat that looks like they are just doing round backed good mornings, then your chance of success with this patient is minuscule if the negative input isn't changed. You have to advise them to substitute appropriate exercise or find a new type of class.
If you can't raise your hands above your head, you don't have the prerequisites to overhead press, let alone catch an Olympic Snatch. That's why your shoulder hurts. Advise as such.
The even trickier minefield is when they come in and they have their own strength coach that they are paying. I ask them what they are doing for "training," and sometimes I'm inwardly just shaking my head. These I don't usually say anything unless I'm specifically asked. Then I'm brutally honest.
I've had endurance athletes be prescribed a prescription of 100 meter sled sprints because they needed a power workout because they got "out kicked" at the last race. Now there feeling some knee pain.
An important thing to note is to not just take exercises away but to substitute better ones. We often hear the story, "Doc it hurts when I run." Doc, "Then don't run anymore." I often take away situps/crunches, but integrate Palloff presses and side planks. I may take a bilateral squat away as we work on hip mechanics and substitute RFESS. I may advise heavier snatch pulls and not a full snatch until the Tspine and GH mobility is present. Instead of full ROM deadlifts, pulling for a 6"blocks.
At the end of the day, I think the right thing to do is the right thing to do. People are their for your expertise as much as your skills. Treat them like you would want to be treated, advise them like you would want to be advised.