What man is, and what man does, determines in what conditions, circumstances and environments he shall be placed. And since man can change both himself and his actions, he can determine what his fate is to be.
To change himself, man must change his thought, because man is as he thinks; and to change his actions, he must change the purpose of his life, because every action is consciously or unconsciously inspired by the purpose held in view.
To change his thought, man must be able to determine what impressions are to form in his mind, because every thought is created in the likeness of a mental impression. To choose his own mental impressions, man must learn to govern the objective senses, and must acquire the art of original thought.
Everything that enters the mind through the physical senses will produce impressions upon the mind, unless prevented by original thought. These impressions will be direct reflections of the environment from whence they came; and since thoughts will be created in the exact likeness of these impressions, so long as man permits environment to impress the mind, his thoughts will be exactly like his environment: and since man becomes like the thoughts he thinks, he will also become like his environment.
But man, in this way, not only grows into the likeness of his environment, but is, in addition, controlled by his environment, because his thoughts, desires, motives and actions are suggested to him by the impressions that he willingly accepts from environment. Therefore, one of the first essentials in the mastery of fate is to learn to govern the physical senses so thoroughly, that no impression can enter mind from without, unless it is consciously desired.
This is accomplished by holding the mind in a strong, firm, positive attitude at all times, but especially while surrounded by conditions that are inferior.
This attitude will bring the senses under the supremacy of the subconscious will, and will finally produce a state of mind that never responds to impressions from without unless directed to do so.
Christian D. Larson (1874-1962)
Excerpt from Mastery of Fate