Zen master Hakuin:

"But, though you spend twenty or thirty years of your life in fruitless effort, and even up to the moment of death fail to break through, you must vow never even for a moment to think that the tales of any decrepit old man or woman can be of benefit to you in any way. If you do, their words will cling to your bones and stick to your skin, and you will never be able to rid yourself of them, to say nothing of achieving the ultimate aim of the patriarchs."