Positive Psychology is an Integrative Therapy, a merging of several forms of theory that has developed its own momentum over the last 50 years, although not new at all! It is working in the hear and now, with clear goals short, medium and long-term defined early on in the process. These goals often develop, tuning the work to a fine degree.
Positive psychology is an enjoyable self-development process, like going to the gym for your psychological and emotional fitness. Makes sense really, we work hard on our physical health (or try to!) so why not invest some time and effort into developing and maintaining our other areas of health. Positive Psychology is a mixture of coaching and psychology and suites those who are functioning already to some degree, as it requires commitment and energy like all keep fit routines do.