'There are nine types of interruptions to developing mental clarity - illness, mental stagnation, doubts, lack of foresight, fatigue, overindulgence, illusions about one's true state of mind, lack of perseverance, and regression. They are obstacles because they create mental disturbances and encourage distractions.'
From The Yoga Sutras of Patanjali (taken from book, The Heart of Yoga - TKV Desikachar) - one of the seminal ancient yoga texts.
