Can't

Can't never could and Won't never will.

Eliminate can't from your vocabulary and those around you.  
I believe this poem best describes why. 

"Can't is the worst word that's written or spoken; 
  Doing more harm than slander and lies;
On it is many a strong spirit broken, 
  And with it many a good purpose dies. 
 It springs from the lips of thoughtless each morning 
  And robs us of courage we need through the day.  
It rings in our ears like timely-sent warning 
  And laughs when we falter and fall by the way.

Can't is the father of the feeble endeavor, 
  The parent of terror and halfhearted work;
It weakens the efforts of artisans clever, 
  And makes of the toiler an indolent shirk.  
It poisons the soul, the person with a vision;
  It stifles in infancy many a plan; 
It greets honest toiling with open derision 
  And mocks at the hopes and the dreams of anyone.

Can't is a word none should speak without blushing; 
  To utter it should be a symbol of shame; 
Ambition and courage it daily is crushing; 
  It blights a person's purpose and shortens their aim, 
Despise it with all of your hatred of error; 
  Refuse it the lodgment it seeks in your mind; 
Arm against it as a creature of terror, 
  And all that you dream of you some day shall gain.

Can't is the word that is foe to ambition, 
  An enemy ambushed to shatter your will; 
Its prey is forever the person with a mission 
  And bows but to courage and patience and skill. 
Hate it, with hatred that's deep and undying, 
  For once it is welcomed back it can break you;
Whatever the goal you are seeking, keep trying 
  And answer to this unwanted thought by affirming, 'I CAN!'"

by Edgar A. Guest