“Age is whatever you think it is. You are as old as you think you are.”

— Muhammad Ali
 

 
“Nothing will work unless you do.”

— Maya Angelou
 

 
“The greatest glory in living lies not in never falling, but in rising every time we fall.”

— Nelson Mandela
 

 
“Never confuse movement with action.”

— Ernest Hemingway
 

 
“Whenever a theory appears to you as the only possible one, take this as a sign that you have neither understood the theory nor the problem which it was intended to solve.”

— Karl Popper