You may have used a magnifying glass to focus the rays of the Sun.
So here’s the thing: the sunlight possesses no particular strength as long as the glass is held at an incorrect angle, or if the glass is moved about and the rays directed from one place to another.
But let the glass be held perfectly still and let the rays be focussed on one spot for any length of time – its effect will become immediately apparent.
So it is with the power of thought.
Let the power be dissipated by scattering your thought from one object to another, you accomplish nothing.
But focus this power through concentration on a single purpose for any length of time and nothing is impossible.