Suffering that makes a man discontented with the life of the ego and spurs him on to seek Self-realisation.
Devotee.: But why should there be suffering now?
Bhagavan: If there were no suffering, how could the desire to be happy arise? If that desire did not arise, how could the quest of the Self arise?
Devotee: Then is all suffering good?
Bhagavan: Yes. What is happiness? Is it a healthy and handsome body, regular meals and so on? Even an emperor has endless troubles although he may be in good health. So all suffering is due to the false notion ‘I am the body’. Getting rid of this is knowledge.
Source: Teachings of Sri Ramana Maharshi in his own words by Arthur Osborne, Chapter Two, section Suffering