 
                            
                        
                        
                        “If you think you can you can, if you think you can't you're right!”
Variant: If you think you can, you can. And if you think you can not, you are right.
“If you think you can you can, if you think you can't you're right!”
“Whether you think you can, or you think you can't — you're right.”
"On Monsieur Coué", Epigram in The Week-end Book (1928), p. 217.
Source: Born to Run: A Hidden Tribe, Superathletes, and the Greatest Race the World Has Never Seen
                                        
                                        Can't Not 
Supposed Former Infatuation Junkie (1998)
                                    
 
                            
                        
                        
                        