Whenever you're down, whenever you're feeling blue, or whenever you're not feeling like yourself.  Whatever the case may be.  Always remember one simple thing: Believe in yourself.

The belief in oneself is one hell of a powerful force.  It can make us move mountains.  Even give us strength beyond belief.  The belief in oneself is the most powerful force around.  Don't let anyone knock you down, make you feel small or anything else.  If you believe in yourself, it will happen.