What is the meaning of [Laugh and the world laughs with you, weep and you weep alone]

If you are in a cheerful mood it is easier to get people to share your
interests and feelings than if you are solemn or sad, when people tend to keep
away from you.

Though the general idea of the proverb was current long before that, it was
given its present form in 1883 by Ella Wheeler Wilcox. It comes in her poem
called _Solitude_ :

> Laugh and the world laughs with you,
> Weep and you weep alone,
> For the sad old earth must borrow its mirth,
> But has trouble enough of its own.