Human beings could be classified under four principal categories according to the attitude they take in life:
(1) Those who live for themselves. They consider everything in relation to themselves and act accordingly. The vast majority of men are like this.
(2) Those who give their love to another human being and live for him. As for the result, everything naturally depends on the person one chooses to love.
(3) Those who consecrate their life to the service of humanity through some activity done not for personal satisfaction but truly to be useful to others without calculation and without expecting any personal gain from their work.
(4) Those who give themselves entirely to the Divine and live only for Him and through Him. This implies making the effort required to find the Divine, to be conscious of His Will and to work exclusively to serve Him.
In the first three categories, one is naturally subject to the ordinary law of suffering, disappointment and sorrow.
It is only in the last category—if one has chosen it in all sincerity and pursued it with an unfailing patience—that one finds the certitude of total fulfilment and a constant luminous peace.
Ref : Some Answers from The Mother