I kinda agree with Kevin. Whilst you do not need to be a musician to appreciate good music you really have to be able to at least understand, to a certain degree, the fundamentals of music construction, meter, rhythm and chord structure to actually write lyrics. Otherwise you are not a lyricist but a POET.
I have seen many poems that people like to call "lyrics" which would require major surgery by a tune-smith to turn them into a song. Any lyricist needs to hear the music, albeit in their head before they can write passable lyrics.
To say that you can write lyrics without understanding music composition or being able to play an instrument is both naive and lazy.