Krishna says (2.56) that Sthithpragna is one who is neither excited by sukh(pleasure) nor agitated by dukh(pain), is free from raag(attachment), bhay(fear) and krodh(anger). This is an extension of 2.38 where Krishna says to treat sukh(pleasure) and dukh(pain); labh(gain) and nasht(loss); and jaya(victory) and apajaya(defeat) with equipoise.
All of us seek sukh but dukh inevitably comes to our lives as both of them exist in pairs of dwandwa(polar). This is like bait to fish where the hook is hidden behind the bait. On the other hand, the struggle always brings rewards.
Sthithpragna is one who transcends these polarities and attains Dwandwa-ateeth. It's a pure awareness that when we seek one, the other is bound to follow -maybe in a different shape and after a lapse of time.
When we get sukh with our planning, ahankaar gets elated which is nothing but excitement however when it turns to dukh, ahankaar gets hurt which is nothing but agitation and krodh implying that it's essentially a game of ahankaar. Sthithpragna realises the same and sheds ahankaar.
Languages rarely have words to describe a state beyond polarities and when Krishna says sthithpragna is free from raag (attachment), it doesn't mean that sthithpragna gravitates towards detachment. It's a state beyond both.
Sthithpragna is free from bhay and krodh but it doesn't mean that they suppress them. They don't leave any space in themselves to let bhay and krodh enter and stay either temporarily or permanently.
Bhay and krodh are projections of the future or the past, on the present. As such, there is no place for either of them in the present moment. When Krishna says that sthithpragna is free from bhay and krodh, it implies that they remain in the present moment.
Source - Daily World