Chögyam Trungpa

If the practice of egolessness begins to become just another way of building up your ego - building your ego by giving up your ego - it is like eating poisonous food; it will not take effect. In fact, rather than providing an eternally awakened state of mind, it will provide you with death, because you are holding on to the ego. So if your reason for sitting or doing post-meditation practice is self-improvement, it is like eating poisonous food. “If I sit properly, with the greatest discipline and exertion, then I will become the best meditator of all” - this is a poisonous attitude.