Unfortunately spirituality is a very tiresome business with little fruit for most people.
A student came to a master and asked for spiritual instruction.
The master, with his stick, drew "pay attention" in the sand.
The student asked again,"pay attention to what master?"
The master again wrote "pay attention " on the sand and said nothing.
The student implored for a third time , and yes you guessed it, the master once again wrote "pay attention" in the sand.
Finally the student understood. He had achieved liberation but not enlightenment.
(This story has been changed by me, feel free to present a better version
edit: so when is enough enough? never or when you've had enough. it's a paradox.