Concentration is an invaluable aid in anything you do, and also vital to any meditation technique. 

Ironically, certain meditations also develop concentration, which is the main purpose of the "counting breath" exercise. However, it also has "integrative effects" on the entire being.

This is a breathing technique that can be done passively or actively - in other words, you can either let your body breathe normally, or control your breathe consciously. Try it both ways, and after a while you’ll be able to tell which method is the most effective for you.

DOING IT:

Start by getting into a sitting position that allows you to be comfortable while maintaining a straight spine. 

Next, start counting your inhalations and exhalations. For instance, when you inhale for the first time, think silently to yourself, "one". Then when you exhale, again think "one". The next time you inhale, do the same thing, but this time count "two". The same with the exhalation. Keep counting silently to yourself like that, until you get to ten. After you reach ten, then start over again from "one".

The goal is to eventually get to where you can do five "sets" of counting one through ten, while you keep your thoughts only on that. If your mind wanders and other thoughts pop in, don't get angry or frustrated, just start over again. 

As with all your exercises, be patient. It takes practice and time to master. As with anything, the more you practice the better you get. If you are consistent and persevere, the results/benefits will eventually come.