Thinking is an activity that, for most of humanity fixes the mind on concrete, external and visible things.
When a person has still not learned that the thoughts can be controlled, it will become wild. And the more it becomes out of control, the more the mind fixes itself on external and concrete things and, the more difficult it becomes to concentrate itself on abstract and elevated things. So, the mind distracts itself, disperses itself, and focuses itself on that which the senses present. And many times the person is not even aware of their own dispersion.
Whoever is conscious of their own state of dispersion and is in a spiritual search, wants to concentrate themselves, because only in this way can they centralize the mental energy and direct it to more elevated levels of existence.
However, in order to concentrate oneself, it is simply not enough to want to do so, nor to also do disciplined exercises. Concentration only in fact occurs when the person gives up whatever attracts, pleases and makes them happy and turns themselves primarily to the spiritual search.
In the past we created many concentration exercises that were appropriate for the mind of those times. But, in general, those who did the exercises had an organized, harmonious, healthy and disciplined life.
This is not the case for most people today. At present, our civilization stimulates consumerism and a form of disorganized life, led by desires. Somebody who today does the concentration exercises created in the past while living as most people do presently, giving in to the appeals of desires, will not be able to concentrate because they will be lacking a certain asceticism in daily life that is indispensable for concentration.
Moreover, with the passing of time, the consciousness and the human mind developed itself and the mind approximated itself to various levels of consciousness. Therefore, ancient concentration exercises are no longer adequate for the present mind.
When one practices asceticism, that is, when one gives up everything that distracts, when one repels everything that does not lead to spiritual levels, when one controls one’s own day by day impulses, concentration can finally take place.
“Spiritual Work with the Mind” pp. 19-21.