Is this not certainly true?
> Your life is not a prewritten narrative with defined story arcs.
It seems to be that someone could believe in the statement before this and not this.
What I understood (due to hastily coming to conclusions) was it is dangerous to believe that life has lows and highs.
Humans are compulsive pattern-recognizers and can turn any arbitrary independent sequence of events into a story.
That doesn't mean the story is wrong, per se, but it does mean you cannot presume to know where a story "is leading up to". Because the only "complete" story is the one that is told afterwards.
[1] http://en.wikipedia.org/wiki/Grand_narrative (lots of "blah" btw)