In the early 80s at least, psychiatry was practiced in smoke-filled consultation rooms, and was all about the mind, not the body or the brain.
It was only a decade later, in the 1990s, that exercise began to be recognized as possibly helpful for treatment of depression and anxiety disorders. Psychiatrists and psychologists began to occasionally recommend that their patients get more exercise, maybe go for a run a few times a week, or join a gym. It couldn’t hurt, we thought, and maybe it would help--patients who struggled with anxiety, ruminations, physical tension, and the like, might at least feel a bit better if they were able to get outside for some fresh air, or work up a sweat on the elliptical machine. There were even a few studies that showed that depression might improve with regular exercise.