Gurudev, in the Bhagavad Gita, Lord Krishna says 'Anityam asukham lokam imam prapya bhajasva mam'. We can understand the anityam (temporary) aspect of this world, but why is it called as asukham (sorrowful)?
That which is temporary is sorrowful. Anityam means which does not exist permanently.
See, before getting a position, a person is worried about getting the position. After he gets the position, he keeps worrying about holding on to it. And when the position is about to go away from him, then he is sorrowful.
So there is misery before getting a position and while holding the position. The fear of its loss gives you sorrow. When it is gone, then also its remembrance gives misery. That is why it is called as asukham. There is no sukha (happiness) in temporary things. Sukha is inside you.
Don’t look for happiness in that which is temporary, that which is fleeting and changing. Joy and happiness is only in that which does not change.