In his book, Raja Yoga, Yogi Ramacharaka (William Walker Atkinson) says about the power of attention:
“The word Attention is derived from two Latin words “ad tendere,” meaning “to stretch toward,” which is really what attention is.
The “I” wills that the mind be focused on some particular object or thing, and the mind obeys and “stretches toward” that object or thing, focusing its entire energy upon it, observing every detail, dissecting, analyzing, consciously and sub-consciously, drawing to itself every possible bit of information regarding it, both from within and from without.
We cannot lay too much stress upon the acquirement of this great faculty, or rather, the development of it, for it is necessary for the intelligent study of Raja Yoga.”
“Attention has been defined as a focusing of consciousness, or, if one prefers the form of expression, as “detention in consciousness.”
“In the first case, we may liken it to the action of the sun-glass through which the sun’s rays are concentrated upon an object, the result being that the heat is gathered together at a small given point, the intensity of the same being raised many degrees until the heat is sufficient to burn a piece of wood, or evaporate water. If the rays were not focused, the same rays and heat would have been scattered over a large surface, and the effect and power lessened.”
“And so it is with the mind. If it is allowed to scatter itself over the entire field of a subject, it will exert but little power and the results will be weak. But if it is passed through the sun-glass of attention, and focused first over one part, and then over another, and so on, the matter may be mastered in detail, and a result accomplished that will seem little less than marvelous to those who do not know the secret.”
“The Attention does not readily fasten itself to uninteresting objects, and, unless interest can be created, it requires a considerable degree of Voluntary Attention in order that the mind may be fastened upon such an object.
And, more than this, even if the ordinary attention is attracted it will soon waver, unless there is some interesting change in the aspect of the object, that will give the attention a fresh hold of interest, or unless some new quality, characteristic or property manifests itself in the object. ”
“This fact occurs because the mind mechanism has not been trained to bear prolonged Voluntary Attention, and, in fact, the physical brain is not accustomed to the task, although it may be so trained by patient practice.”
Excerpted from Raja Yoga by Yogi Ramacharaka (William Walker Atkinson).
You can develop the power of attention by practicing concentration exercises.
You can find information, tips and advice about the power of concentration, together with exercises and instructions in the book How to Focus Your Mind.