"The calm comes naturally."
Hmm, I took a shot and "Die Ruhe kommt selbst" was accepted. Just commenting for the record.
"Ruhe" in this sentence should be translated as "stillness", "tranquility", "silence" that may come to you while meditating; it comes to you "naturally" ie. without any effort; "natural "inner peace" as contrasted to man-made "noise and busyness", "die Ruhe kommt von allein" = "stillness/peace will find you, if you give it a chance"; Enjoy
That translation is using the sense of the word “naturally” as: "used to describe something that happens or exists by itself without being controlled or changed” (to quote one of Merriam-Webster’s online definitions).
When you use that definition of “naturally”, it fits, because it happens by itself, i.e., from itself/from alone… von allein.
The rest comes by itself is not a proper sentence in German Better: Die Stille kommt von allein. But: The sentence is contrived