My Webster's defines 'welfare' as follows: the good fortune, health, happiness, prosperity, etc.) of a person, group, or organization; wellbeing. Obviously the lexicographers have tried their best to give as accurate a definition as possible, bur merely having fortune and health does not guarantee that a person can be made happy. And unfortunately in the end everything is finished at death.

When Srila Prabhupada founded ISKCON (International Society for Krsna Consciousness) he made it clear that this society will follow Lord Caitanya Mahaprabhu's instruction that those who have taken birth as human beings as Indian, on the land of "Bharatavarsha", they should learn their spiritual asset and distribute it throughout the world for real welfare activity."
What then is 'real welfare activity'?
"Real welfare work, whether individual, social, or political, should help prepare a person for his next life and help him reestablish his eternal relationship with the Supreme."
The activities described by lexicographers are limited to the material body or at the most to the mind, intellect, and the ego. But real welfare activity means to see the interest of the soul. And what exactly is the interest of the soul? The interest of the soul is that the soul is part and parcel of Krsna, God. Just like small spark of fire is part and parcel of the big fire, similarly, we living entities, we are very minute, small spark of the Supreme Brahman, Parabrahman, or Krsna. So as the spark within the fire looks very beautiful, the fire also looks beautiful, and the spark also looks beautiful, but as soon as the sparks fall down from the fire, it becomes extinguished.
Another important consideration is the sanctioning authority. Who is sanctioning a particular welfare activity? Just like someone helping a condemned prisoner escape from the prison may himself land in jail or when a sick patient's friend provides him foods forbidden by the doctor, he is putting the patient's life in danger. In the case of the prisoner when the state executive head excuses him then he is free. Similarly no welfare activity can help anyone unless it is sanctioned by Lord Krsna, the Supreme Personality of Godhead. The welfare provider has to be Krsna conscious and the recipient of his service also should be trained in Krsna consciousness.
In a conversation Srila Prabhupada summed up the matter: Just like there is a tree, and the whole tree is full of branches, twigs and leaves and flowers and fruits. So somebody is wate ring the fruit , somebody is watering the leaf, somebody is watering the branches, somebody the twigs, but everyone is improper. One who is watering the root, he's perfect. He knows how to do things. If you water the root of the tree, it will go to the twigs, it will go to the leaves, it will go to the fruit, it will go to the flower.
One who does not know the root, however he might be working very diligently for the poor humanity or community or society, they will never be successful to gain the result peace and prosperity. They are forgetting the root. And root is God. So they must put water in the root. Then it will be all right; otherwise, it will be all failure. The history of the world is like that. They are trying for the nation, for the society, for the community, and for the family, but everything has become unsuccessful.
(Syamananda Dasa)