Different people may describe "wellness" in different ways... however, most would agree that:
The definition of wellness, long used by the National Wellness Institute is consistent with these tenets. Wellness is an active process through which people become aware of, and make choices toward, a more successful existence.
Information from https://libguides.tcu.edu/WellnessGuide
It is a lifestyle. A way of living that encourages good physical and mental health. It is a balanced lifestyle that includes an emphasis on the body, mind and soul. Wellness is the integration of physical, mental, and spiritual well-being, in an effort to achieve a more fulfilling and gratifying life.
Wellness is important because it shapes nearly every aspect of everyday life. Physical wellness allows you to move around without pain, for example, so you can function well while working, doing housework, or playing sports. Poor physical wellness, by comparison, can make it difficult to engage in any physical activity at all without being in pain, dizzy or short of breath. Emotional wellness helps you process grief, anger, or frustration during life’s inevitable downturns and helps you experience joy and optimism when things are going well. Social wellness gives you a shoulder to cry on and someone to celebrate with.
In short, wellness helps you stay on track and move forward down the path towards a fulfilling life, even when the road gets rough.
Information from https://libguides.tcu.edu/WellnessGuide