"There are two practices -- concentration and meditation. For the first year or two, you probably will be almost exclusively practicing concentration. You will try meditating, but it won't come until later... When you concentrate, you're focusing on something. When you meditate, you're letting go and dissolving, you're seeking to stop all thought.
"It is very hard to stop your thoughts. Try it. Not to have one thought, image, idea, or associative feeling in the mind is difficult for most people. Rather than just trying to stop your thoughts, which is hard and frustrating, it's easier to concentrate and focus on something. As you focus completely on something, all other thoughts will be forced out of the mind because your attention will be dominated by the object of concentration. This develops your mental power exquisitely." Rama - Dr. Frederick Lenz
This is talk 9 of 18 in the Zen Tapes series.