Unquote #11 answer

The quote

It means your future hasn't been written yet. No one's has. Your future is whatever you make it, so make it a good one.

The puzzle as it was set

YV XSMFQ NUKH EKVKHS DMQF'V ISSF OHYVVSF NSV. FU UFS'Q DMQ. NUKH EKVKHS YQ ODMVSPSH NUK XMJS YV, QU XMJS YV M CUUG UFS.

The key

Each code letter stood for one real letter (code letter, then the real letter it hid):

M → AI → BG → DS → EE → FC → GD → HY → IJ → KX → MF → NU → OH → RQ → SV → TK → UP → VO → WN → Y

The most frequent code letter was S (13 times), which stood for E. Short words, apostrophes and repeated letters are the usual way in: a one-letter word is almost always A or I, and THE is the commonest three-letter word in English.