Krishn describes equanimous person:

'Equanimous (person) never grieves. Neither for living nor for dead. He is without attachments. He has no attachments to good through love nor to bad through hatred. He does not have anger nor fear. He faces adversity and prosperity, failure and success without grief and joy.'

He does not hate bad nor love good but understands that it is the matter of ignorance that misdeeds are committed because the sinner is not aware of the outcomes of his actions.

He also knows that an individual is supposed to do his duty let result be any. If the doer is happy with success and unhappy with failure, he has to face outcome of the action in subsequent lives. Equanimity is utmost essential to acquire the divine bliss.

‘On birth, death is certain and on death, birth is certain. Why to worry for unavoidable?’

If sun rises, it has to set and if sun sets, it has to rise. So is the life. Hence birth and death are not the matter of joy and grief but they are as natural phenomenon as sunrise and sunset.

‘Something which is not existing will never come into existence and something which is existing will never cease to exist.'

That is soul is indestructible and hence why do you cry? For body? It is lying there in front of you. Thus Gita has plenty of verses advocating detachment.