Maxwell Maltz said this quote
“ What is opportunity, and when does it knock? It never knocks. You can wait a whole lifetime, listening, hoping, and you will hear no knocking. None at all. You are opportunity, and you must knock on the door leading to your destiny. You prepare yourself to recognize opportunity, to pursue and seize opportunity as you develop the strength of your personality, and build a self-image with which you are able to live -- with your self-respect alive and growing. ”