Everyone has his own specific vocation or mission in life; everyone must carry out a concrete assignment that demands fulfillment. Therein he cannot be replaced, nor can his life be repeated, thus, everyone's task is unique as his specific opportunity to implement it.
For the meaning of life differs from man to man, from day to day and from hour to hour. What matters, therefore, is not the meaning of life in general but rather the specific meaning of a person's life at a given moment.
All that we are is the result of what we have thought. If a man speaks or acts with an evil thought, pain follows him. If a man speaks or acts with a pure thought, happiness follows him, like a shadow that never leaves him.