The above is a well known saying and it is true.

Do you find yourself thinking mainly about all the bad things that
have happened in your life ?.

Do you look at the future and assume that things are always going
 to turn out badly for you ?.

Have you ever decided on a new years resolution or tried to set
a goal but failed to stick to it ?.

Millions of  people have goals they are initially excited about only
 to find a few days or weeks into it that they have lost all
 their motivation to continue.