'In Zen, practitioners use kung-an (koans) as subjects for meditation until their mind comes to awakening. There is a big difference between a kung-an and a math problem the solution of the math problem is included in the problem itself, while the response to the kung-an lies in the life of the practitioner. The kung-an is a useful instrument in the work of awakening, just as a pick is a useful instrument in working on the ground. What is accomplished from working on the ground depends on the person doing the work and not just on the pick. The kung-an is not an enigma to resolve this is why we cannot say that it is a theme or subject of meditation.
It is not the number of books you read, nor the variety of sermons you hear, nor the amount of religious conversation in which you mix, but it is the frequency and earnestness with which you meditate on these things till the truth in them becomes your own and part of your being, that ensures your growth.
If one's life is simple, contentment has to come. Simplicity is extremely important for happiness. Having few desires, feeling satisfied with what you have, is very vital satisfaction with just enough food, clothing, and shelter to protect yourself from the elements. And finally, there is an intense delight in abandoning faulty states of mind and in cultivating helpful ones in meditation.