Here’s an interesting quote by Charles Haanel:

“Yet there are many who are not ready to enter into the discipline necessary to think correctly, even though it is evident that wrong thinking has brought failure.

Thought is the only reality; conditions are but the outward manifestations; as the thought changes, all outward or material conditions must change in order to be in harmony with their creator, which is thought.

But the thought must be clear cut, steady, fixed, definite, unchangeable; you cannot take one step forward and two steps backward, neither can you spend twenty or thirty years of your life building up negative conditions as the result of negative thoughts, and then expect to see them all melt away as the result of fifteen or twenty minutes of right thinking.

If you enter into the discipline necessary to bring about a radical change in your life, you must do so deliberately, after giving the matter careful thought and full consideration, and then you must allow nothing to interfere with your decision.

This discipline, this change of thought, this mental attitude will not only bring you the material things which are necessary for your highest and best welfare, but will bring health and harmonious conditions generally.

If you wish harmonious conditions in your life, you must develop an harmonious mental attitude.

Your world without will be a reflection of your world within.”