Sudden sad ? why ?

ASSALAMUALAIKUM W.M.T

Haaa ~ this is weird . I got sad and I dunno why !
what is sadness actually ?

"Sadness is a feeling — it's one of the many normal human emotions, or moods, we all have. Sadness is the emotion people feel when they've lost something important, or when they have been disappointed about something, or when something sad has happened to them or to someone else."

Do I lost something ?
(of course . everyone do lost something in their life . . )

Do I disappointed ?
(yeahh . disappointed . . )

Does everone else sad ?

(I pretty sure, I dunno . . )

When Is It Natural to Feel Sad?

One of the reason is when you don't feel great about yourself . .

yup . I'm no great at all . haha .