Are you an unusually persevering and persistent person? Or, like most of us, do you sometimes find it difficult to stick to the job until it is done? What is your usual experience in this respect?
Is it not this, that you work steadily along until of a sudden you become conscious of a feeling of weariness, crying "Enough!" for the time being, and that you then yield to the impulse to stop?
[Sidenote: The Lagging Brain]
Assuming that this is what generally happens, does this feeling of fatigue, this impulse to rest, mean that your mental energy is exhausted?
Suppose that by a determined effort of the will you force your lagging brain to take up the thread of work. There will invariably come a new supply of energy, a "second wind," enabling you to forge ahead with a freshness and vigor that is surprising after the previous lassitude.
Nor is this all. The same process may be repeated a second time and a third time, each new effort of the will being followed by a renewal of energy.
