Let every man feel that he is the architect and builder of his own life, and that he proposes to make a success of it by working.

This quote means that each person should believe that they are responsible for creating their own life and that they are capable of achieving success if they work hard. It is up to each person to decide the course of their life and put in the effort to make it successful. If someone wants to achieve success, they should take responsibility for their own life and make a plan, do the work, and keep going. With dedication and hard work, they can create the life they want.