Refocusing your attention and developing the ability to stay focused is great for your brain power. These practices are generally referred to as mindfulness practices.
One of the most basic forms of meditation is simply sitting (or laying) and paying attention to your breath. When you notice that your thoughts are wandering, simply refocus on your breath. The act of refocusing your mind back to the simplicity of your breath can be seen as a repetition – if you will. Repeating this action has the potential to strengthen your ability to maintain focus.