Not bad at all!
"Venir al mundo" is a set expression with the meaning you intend.
"Dejar el mundo" is not a set expression, but it's the most common collocation.
When you describe the way one should leave this world, you're using an adverbial phrase. As the main verb is "leave" and that action is being proposed as executed in the context of the whole paragraph, what mood do you think a Spanish speaker should choose to express the notions of "smiling" and "crying"?
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[gone]
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