On a clear, bright sunny day take powerful magnifying glass and a stack of newspapers and go outside for an experiment. Hold the magnifying glass over a pile of crumpled pages. Even though you are magnifying the power of the sun's rays through the glass lens, you will never start a fire - if you keep moving the glass.
But if you hold the magnifying glass still, allowing it to focus the rays in a concentrated beam of sun energy, you harness the power of the sun and multiply it through the lens - starting a fire.
Focusing also works with your power of thought! Try it and ignite your wandering ideas.