It is one of the factors of enlightenment. In the
4th stage of concentration meditation there is a state
that is describe as ‘neither pain no not pain’ even though physical
pain and discomfort are ever present. It is so because the mind is
already so calm and settled it is unaffected by it any
more.
Equanimity is certainly not about indifference,
which is a state of inaction when things are not right and/or it
does not concern us and we do nothing to correct the situation.
This would be a very unskillful act.
It is a quality that will increase with a
decrease in one’s craving and clinging. As it become more
established one can expect ill-will, anger and hatred to decrease
and such other qualities as patience and forgiveness to become a
strong feature in the person.
One can say that when it is fully cultivated, the
mind will always be at rest and at peace with itself and such a
person would have a calm, serene disposition and be able to face
any situations in a fearless manner when so required.