How to get rid off constant sadness?

you dont. this isn't meant to be a discouraging statement. i live in a desert, and the question to "how do i get rid of constant heat" doesn't have an answer, like " just stop being hot" or "try to think cold". when you have depression, you can treat it as a problem, with a solution, but never the idea of a permanent solution. air conditioning needs fuel. happiness need work. find something you can monitor and make effort to maintain. if you find nothing you have on hand fills the requirement , then search for the next piece, as humanity is more jigsaw, and less tetris

Get out of your comfort zone, break your mundane routine do something new, chances are the excitement will kill the sadness

Just as our resident dentist said, find new ways to entertain yourself. Play hide and seek with the Godzilla.

Laugh and the world laughs with you - said Shakespeare before writing Romeo and Juliet.