When we examine this accession of energy we find it to be describable in several ways—­physiologically, neurologically and psychologically.  The physiological effects consist in a heightening of the bodily functions in general.  The muscles become more ready to act, the circulation is accelerated, the breathing more rapid.  Curious things take place in various glands throughout the body.  One, the adrenal gland, has been the object of special study and has been shown, upon the arousal of these reserves of energy, to produce a secretion of the utmost importance in providing for sudden emergencies.  This little gland is located above the kidney, and is aroused to intense activity at times, pouring out into the blood a fluid that goes all over the body.  Some of its effects are to furnish the blood with chemicals that act as fuel to the muscles, assisting them to contract more vigorously, to make the lungs more active in introducing oxygen into the system, to make the heart more active in distributing the blood throughout the body.  Such glandular activity is an important physiological condition of these higher levels of energy.  In neurological terms, the increase in energy consists in the flow of more nervous energy into the brain, particularly into those areas where it is needed for certain kinds of controlled thought and action.  An abundance of nervous energy is very advantageous, for, as has been intimated in a former chapter, nervous energy is diffused and spread over all the pathways that are easily permeable to its distribution.  This results in the use of considerable areas of brain surface, and knits up many associations, so that one idea calls up many other ideas.  This leads us to recognize the psychological conditions of increased energy, which are, first, the presence of more ideas, second, the more facile flow of ideas; the whole accompanied by a state of marked pleasurableness.  Pleasure is a notable effect of increased energy.  When work progresses rapidly and satisfactorily, it is accomplished with great zest and a feeling almost akin to exaltation.  These conditions describe to some degree the conditions when we are doing efficient work.

Since we are endowed with the energy requisite for such efficient work, the obvious question is, why do we not more frequently use it?  The answer is to be found in the fact that we have formed the habit of giving up before we create conditions of high efficiency.  You will note that the conditions require long-continued exertion and resolute persistence.  This is difficult, and we indulgently succumb to the first symptoms of fatigue, before we have more than scratched the surface of our real potentialities.