It's counterintuitive, but happiness is sustained only by fulfilling our obligations; doing our duty and if your determined to fulfill your duty then you can make it through life.
As a student its our duty to study
As a job seeker its our duty to work towards our carrier
As a parents we have duty towards our children’s, and as son or daughter we have duty towards our parents.
As a citizen we have duty towards our nation.
now fulfillment of duty is a tough task.