“It’s alright, now count 1, 2, 3 and forget.
Erase all sad memories.
Hold each other’s hands and smile.” - lyrics from 2!3! by BTS

Rather than dwell on your sadness, just count 1, 2, 3, forget and move on. Don't stick to your downs. You have to cope up by doing positive ways, firstly by smiling.

Share your worries or things that bother you to your friends, family or people you can trust or you trust. It's really okay to open up to someone else. Let your feelings explode. Shout. Scream. Cry. Let it all out. Let it go. Once you do that, the heavy feeling will lessen, might as well lift mind better. 

Then smile.