Which is dead wrong. Exercise is good for humans, depressed or not.

You also said, "Before I turned twenty I met two people my age who took your advice and exercised until ambulances had to pick them up (literally). "

...apparently as a warning that exercise is dangerous. But as you can see, it's a ridiculous statement.

Sure, people should see a therapist. They should also exercise. Go for a walk. Move around. They should also gain some sleep discipline. Those are easy to start with. There's no mutual exclusion here. Just because someone is exercising and sleeping right, does not mean they cannot talk to a therapist.