Self-confidence.
No, there is this factor in all success: self-confidence. If we analyze this, we find that it means that one is aware that all one's mental and physical faculties are working harmoniously. The deadliest and subtlest enemy of that feeling is anxiety about the result; the finest gauze of doubt is enough to dim one's vision, to throw the entire field out of focus. Hence, even to be aware that there is a result in prospect must militate against that serenity of spirit which is the essence of self-confidence. As you will know, all our automatic physiological functions are deranged if one is aware of them. This then, is the difficulty, to enjoy consciously while not disturbing the process involved.
Introduction
Aleister Crowley
Magick Without Tears
New Falcon Publications, 1991
page 21