So the most difficult thing is always to keep your beginner's mind. There is no need to have a deep understanding of Zen. Even though you read much Zen literature, you must read each sentence with a fresh mind. You should not say, "I know what Zen is," or "I have attained enlightenment." This is also the real secret of the arts: always be a beginner. Be very very careful about this point. If you start to practice zazen, you will begin to appreciate your beginner's mind. It is the secret of Zen practice.
When we talk of compassion, we usually mean working with those less fortunate than ourselves. Because we have better opportunities, a good education, and good health, we should be compassionate toward those poor people who don't have any of that. However, in working with the teachings on how to awaken compassion and in trying to help others, we might come to realize that compassionate action involves working with ourselves as much as working with others. Compassionate action is a practice, one of the most advanced. There's nothing more advanced than relating with others. There's nothing more advanced than communication -- compassionate communication.
Source: When Things Fall Apart : Heart Advice for Difficult Times (Shambhala Classics)
The mind exists in a state of "not enough" and so is always greedy for more. When you are identified with mind, you get bored and restless very easily. Boredom means the mind is hungry for more stimulus, more food for thought, and its hunger is not being satisfied.
When you feel bored, you can satisfy the mind's hunger by picking up a magazine, making a phone call, switching on the TV, surfing the web, going shopping, or — and this is not uncommon — transferring the mental sense of lack and its need for more to the body and satisfy it briefly by ingesting more food.
Or you can stay bored and restless and observe what it feels like to be bored and restless. As you bring awareness to the feeling, there is suddenly some space and stillness around it, as it were. A little at first, but as the sense of inner space grows, the feeling of boredom will begin to diminish in intensity and significance. So even boredom can teach you who you are and who you are not.
You discover that a "bored person" is not who you are. Boredom is simply a conditioned energy movement within you. Neither are you an angry, sad, or fearful person. Boredom, anger, sadness, or fear are not "yours," not personal. They are conditions of the human mind. They come and go.
Nothing that comes and goes is you. "I am bored." Who knows this? "I am angry, sad, afraid." Who knows this? You are the knowing, not the condition that is known.
There are people who sit there their entire lives in the lotus position and breath in and out. They can sit there until they die, but without practicing in the physical world what they are experiencing in meditation, they will not progress spiritually beyond that point. One must practice in the physical realm and become a walking, living, breathing meditator. Not a person just sitting with their eyes closed, but the meditator with his eyes open in the world and acting in the world from a place of peace, silence, stillness and most importantly the place of being a witness. Only then does one become a true meditator in life. Until that time they are just practicing, they are still just practicing.
Swami Sai Premananda
Source: Principles of Higher Living: The Western Experience Upon the Shores of Eastern Wisdom
We must know that it is not enough just to see what the Mind is, we must put into practice all that makes it up in our daily life. We may talk about it glibly, we may write books to explain it, but that is far from being enough. However much we may talk about water and describe it quite intelligently, that does not make it real water. So with fire. Mere talking of it will not make the mouth burn. To know what they are means to experience them in actual concreteness. A book on cooking will not cure our hunger. To feel satisfied we must have actual food. So long as we do not go beyond mere talking, we are not true knowers.
Takuan Soho (1573 - ?)
Source: Takuan's Letter to Yagyu Tajima No Kami Munenori on the Mystery of Prajna Immovable - as found in Daisetz T. Suzuki's book, Zen and Japanese Culture