How can psychologists find their niche?

The American Psychological Association has 53 divisions representing various subfields of psychology yet there are still far more specific areas in which to specialize. Whether just starting out or looking to expand or make a career change, finding a niche within psychology can feel overwhelming. How does one decide what path to choose?
Beyond the main career paths of teaching, research, or clinical psychology, or a combination of all three, the options for where you specialize or where you work are endless.
With an ever-changing health care market, business world, and cultural shifts, options for psychologists are constantly expanding. It was once novel to have a therapist embedded in a medical practice and we are now seeing this model eve...