Source: The Hindu universe

In Vedic times, the normal human life was regarded as eighty-four years, consisting of four sections of twenty-one years each. The first twenty-one years is called the "Brahmacharya ashram", the stage of youth or learning, which requires a certain discipline, guidance and purity for its full flowering.

The second twenty-one years, from ages twenty-one to forty-two, is called the "Grihastha ashram" or householder phase. This is the main time for having children and raising a family, as well as for working and fulfilling our duties to society. 

The third section of twenty-one years, from ages forty-two to sixty-three is the "Vanaprastha" or the hermitage phase. This is a time for return to contemplation and for guiding society in the distance.

The fourth and last section from sixty-three to eighty-four is the "Sannyasa" or renunciation phase. The person, now an elder full of wisdom, inwardly aims to renounce all the outer goals of life. He also becomes a teacher of the spiritual knowledge and no longer partakes in social or political concerns.
In this we see that only twenty-one years are allotted for the outer duties of life. Three-quarters of life is to be devoted primarily to spiritual study.

Photo on the lefe SWASTIKA which symbolises, four ashramas, four directions , four vedas and four seasons. ( Germany proposes to ban this symbol? read the next post )

Thanks : The Hindu Universe