In the Bhagavad Gita, Stithpragya is called a sage/ Muni. Simply put, Sthitipragya means equality between happiness and unhappiness. It is to be comfortable and calm even in the face of impulses like attachment, jealousy, lust, anger and greed.
Isthiti Pragya means to be situated in one’s own intelligence which is beyond external perceptions and above ideological bonds. To know one’s own intelligence, it is necessary to know and feel the soul. In order to feel the soul, one has to be spiritual. After a while of making spiritual progress, the soul becomes realized (Pragya).
The seeker whose mind is not restless with sorrows, whose longing for pleasure vanishes, who becomes free from fear and anger, who does not have affection for anything, who is not happy about receiving good things and is not sad after receiving something bad is called Stithpragya or a Muni.
To become a Stithpragya, one needs to withdraw the senses from worldly objects which will eventually cause the intellect to become stable. By this, the restlessness of the mind is removed and the person will possess a steady intellect.
Stithpragya does not mean that one should withdraw oneself from worldly objects and worldly responsibilities. We still have to do our work but we should not be happy with good results or unhappy with inauspicious results. In every situation, we have to live with the same spirit.