In a sense, every career is a psychology career. Whether you're a salesman, a schoolteacher, or a sports coach, to be effective—and especially to advance in your line of work—you often need a fine-tuned understanding of what motivates people.
Psychology itself is hardly a monolithic field. Careers that require formal training in psychology are incredibly varied. Providing clinical psychotherapy is very different from conducting neuroscience research in a laboratory. People who work in psychology-related fields may be trained as psychologists, social workers, school counselors, researchers, or medical doctors. What's more, formal training in psychology can be useful in many fields; an in-depth understanding of human motivation, for example, can be especially valuable for those seeking careers related to marketing or advertising. In addition, training in psychology can provide information that is particularly helpful for those in or seeking leadership positions in any field.