Well-being is basically another term of referring to mental health.
According to the World Health Organization (WHO), it is
“A state … in which the individual realizes his or her abilities, can cope with the normal stresses of life, can work productively and fruitfully, and can contribute to his or her community”.
Our well-being is basically what is good for us.
It can be hard to have a specific set of factors that completely determine our well-being. Our well-being includes mental, physical, environmental and socio-cultural factors.
So we cannot always manage all of those elements all of the time.
There are times when certain elements that affect our well-being will be outside of our control.
What is important for your well-being is focusing on what you can do for yourself.