Here is an excerpt from my book, The Silent Master: Awakening the Power Within:
Concentration means that you will mentally focus on something an idea, a feeling, a concept and eliminate everything else from your mental environment. Concentration does not come easily to the modern mind which has been over stimulated by the constant, aggressive sights and sounds of the media. Television alone has done a lot to turn us into couch potatoes, teaching us to be passive victims of outside stimulation. You must become able to shut out outside stimulation and turn within. It takes full attention to concentrate properly, and you may have to train yourself before you can do it well.