Enthusiasm is that ingredient of vitality mixed with a firm belief in what you are doing that ensures the success of any project you undertake.
Dale CarnegieSo, to prevent fatigue and worry, the first rule is: Rest often. Rest before you get tired.
Dale CarnegieEnthusiasm is the dynamics of your personality. Without it, whatever abilities you may possess lie dormant; and it is safe to say that nearly every man has more latent power than he ever learns to use. You may have knowledge, sound judgment, good reasoning faculties; but no one-not even yourself-will know it until you discover how to put your heart into thought and action.
Dale CarnegieI once succumbed to the fad of fasting and went for six days and nights without eating. It wasn't difficult. I was less hungry at the end of the sixth day than I was at the end of the second. Yet I know, as you know, people who would think they had committed a crime if they let their families or employees go for six days without food; but they will let them go for six days, and six weeks, and sometimes sixty years without giving them the hearty appreciation that they crave almost as much as they crave food.
Dale Carnegie