WHAT DO YOU EXPECT?

"Life is largely a matter of expectation."

Horace (BC 65-8) Latin lyric poet.

Since we often don't expect things will turn out good we don't work hard to make them so, and as a result, guess what? 

Self-fulfilling prophecy, they don't.

However the reverse is true as well.

Put in the effort, work hard, and your expectations can be fulfilled.