Let's know: Why do humans do so much devotion, yet remain unhappy?

  This is how it happens that if a person is dependent on the virtues of his previous births, then if a person does not perform any duty or worship And someone has committed more sins: then he gets happiness or sorrow in the present life on the basis of the sins or virtues he did in the previous birth.  

So on the basis of the ratio of sins or virtues of the previous birth of any human being in human birth, happiness or sorrow is found in the present.