Here’s an interesting quote by William Walker Atkinson:
“One can, by continually keeping the mind in certain channels, so train and develop the faculties that they will soon take up the new habit of thought and will, without effort, follow the new mental path that has been mapped out for them. Remember, each time you think a thought, or act out a thought, you make it that much easier for your mind to do the same thing over again.
If you wish to be Energetic and Active, think as many energetic and active thoughts as you can and endeavor to act them out. Let your thoughts be constantly upon these subjects and endeavor to manifest the thought in action as much as possible. By following this course you will gradually make yourself over, so far as those habits are concerned, and the new way will be the natural way, and the old discarded habits will seem very unreal to you. One can train his mind in any direction desired, or considered needful. Remember, it is the conscious mentality training and shaping the sub‑conscious. You are filling the sub‑conscious storehouse with the goods you wish to use, and when you have occasion to bring out any of these mental goods you may expect to find only those which you have placed there.
The sub‑conscious mentality may be trained just as one would train a child or pet animal. It may be moulded and shaped according to the will. It requires perseverance, of course, but it is an important thing to accomplish.
We have been servants of our minds for so long that we have grown to consider that state of affairs beyond remedy, and, although we do not like it, we have about resigned ourselves to the inevitable. The New Thought carries the message of mental freedom to Man. It shows him that the mind is but a tool of the Real Self—an instrument to be used—a machine that can be taught to do his bidding.
If the Desire is in a man he can mould his mind to carry out his desires and aspirations. If a man lacks certain qualities, he may develop and grow these desirable qualities by constantly carrying them in mind and manifesting them in action as often as may be. And if one wishes to overcome certain weak thoughts and tendencies he may do so by holding the thought exactly opposite to the one he wishes to overcome. He is in control if he will only assert himself. He is master of the warehouse and has the power to admit only such goods as he considers desirable.
You are building up your mind constantly—you are erecting the edifice of character every day. How are you building it — what materials are you using in the edifice? Are you using the best material possible—the positive, bright, confident thought materials? Or are you using the defective, imperfect, negative, fearful materials that so many have used? While you are building up your mind, why don’t you do it right? Why don’t you insist upon nothing but the best material being used and reject all of the undesirable kind? You have the operation in hand—you are the builder. If you make a poor job of it, don’t blame anyone but yourself. You are building today— what kind of material are you using?”