The big distinction about wellness psychology is that it is largely a manifestation of your identity, who you believe yourself to be. If you consider yourself a well person, it goes a long way toward producing well habits and a well mind. Your identity is your self image, your self concept, your beliefs and your values. Choosing beliefs and values that are consistent with well behaviors leads to a well mind.
For example, if you were told as a child that if you washed your hair and went outside with a wet head, you'd get sick, there's a good chance you either don't do that, or when you do, you either get sick or worry that you will. This belief, imposed on you by well-meaning but misguided advisors, has no grounding in fact, so merely noticing when you dredge up stuff like this and challenging it to see if it's really true for you can eliminate interference to normal function caused by faulty thinking. You'll actually heal better and faster when you catch yourself in these limiting beliefs and adjust them.
Your identity is based on your sense of self, which largely came from the beliefs of such well-intentioned people who shaped your early life - as Dr. Larry Markson says, your Mothers, Fathers, Teachers and Preachers, MFTP. Discovering the beliefs that prevent you from expressing yourself as you wish, and replacing them with beliefs that empower you and help you grow, lead to a well psychology.
Examine your values, what you consider to be important, and be sure they match your ideals. Honoring your innermost needs and wants instead of denying them creates an internal environment of self-acceptance, integrity and inner peace. Love, respect, honesty, freedom - everyone has a different formula, and investigating yours can help you feel more comfortable in your own skin.