The very fact of observation alters the observer and the observed. After all, what prevents the insight into one's true nature is the weakness and obtuseness of the mind and its tendency to skip the subtle and focus on the gross only. When you follow my advice and try to keep your mind on the notion of 'I am' only, you become fully aware of your mind and its vagaries. Awareness, being lucid harmony (sattva) in action, dissolves dullness and quietens the restlessness of the mind and gently, but steadily changes its very substance. This change need not be spectacular; it may be hardly noticeable, yet it is a deep and fundamental shift from darkness to light, from inadvertence to awareness.