Great Article About Controlling Your Attention to What Matters written by one of my favorites!

Controlled Attention by Napoleon Hill

Controlled attention can be likened to a gardener who keeps his fertile garden spot cleared of weeds so that he can make it yield edible foods. The simile is perfect, for it is well known that the habit of neglecting to keep the mind filled with positive thoughts results in its becoming filled with the weeds of things one does not want.
You must either take charge of your mind and, by controlled attention, feed it the type of food you wish to produce, or you must pay the penalty of having your mind taken over by the negative influences of your environment. There is no compromise between these two circumstances. You either take possession of your mind and direct it toward the attainment of your major definite purpose, or your mind will take possession of you and give you whatever the circumstances of life hand out.
The choice, however, is within the control of every human being. The very fact that the power of thought is the only thing over which any human being has been given the right of complete control is highly suggestive of the huge potentialities available through the exercise of this profound prerogative.
Once you understand this principle of autosuggestion, it will be easy for you to understand why your mind should be kept busy at all times, in pursuit of a definite major purpose. That will keep your mind out of mischief and force it to work for you – not against you.
To summarize, autosuggestion is the tool with which we dig a mental path in the brain. Controlled attention is the hand that holds that tool. Habit is the map or blueprint which the mental path follows. An idea, or a desire to become transformed into action, must be held in the conscious mind until habit gives it permanent form. From there on autosuggestion does the rest by transferring the pattern to the subconscious mind where it is taken over and automatically carried out to its logical conclusion, by whatever practical means may be available to the individual.
Source: PMA Science of Success Course. Educational Edition. The Napoleon Hill Foundation. 1961. Pgs. 347-348.