Many Ph.D.-level psychologists stay in the field of teaching at the college and university level. Typically, Ph.D. programs allow graduate students to teach and assist in lower-level psychology classes, and many continue on that path. Professor jobs are available at your home university and around the country at all levels of education.
If you choose to be a professor, often that will have research opportunities as well. But if research is your first love, not teaching, there are many opportunities in the public and private sectors dedicated to psychological research. The National Institutes of Health often sponsor studies and research projects relating to enhanced mental health.
Clinical and counseling psychologists are trained specifically for mental health therapy. Therapy offers many pathways to mental health, including diagnosis and processing. Psychologists practicing in therapy treat mental illnesses and work with a patient to change unhealthy behaviors.
One growing field that many psychologists enter annually is the industrial-organizational field of psychology. I-O psychology is the study of how businesses and organizations function and how they can function better. Often, psychologists are brought on staffs at businesses for consulting purposes. They help clients become as productive as possible, while not sacrificing the health and well-being of their employees. Others recruit, interview and monitor employees.