I do not know the purpose of this life!! This is what many great spiritualist are finding it out. Whatever they have said if their opinion. So in this world we have wants, when those wants dont meet our expectations or requirements then we feel disappointed! Expecting less would be one of the major key for being happier and lesser disappointments. Being proactive is another.
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Moments of disappointments & depressio are boumd to occur in our life but we must not allow them to overwhelm us & stop us in our work. In such moments we shd remember that 'Rome was not built in a day' & take up up our work. Success is sure to come.