Karuna is not merely showing pity or compassion and shedding tears of despair at the misery (duhlcba) of others.
It is compassion coupled with devoted action to relieve the misery of the afflicted. The yogi uses all his resources - physical, economic, mental or moral - to alleviate the pain and suffering of others. He shares his strength with the weak until they become strong. He shares his courage with those that are timid until they become brave by his example. He denies the maxim of the 'survival of the fittest', but makes the weak strong enough to survive. He becomes a shelter to one and all.