The Reason For Our Endless Sufferings

When we understand the evolution of our unsatisfactory experiences in cyclic existence, we will see that meditating on emptiness is their antidote. All knowable things--people and phenomena--appear to our minds to be inherently existent. We then grasp at them as existing inherently. Our inappropriate attention focuses on them, and that gives rise to the various disturbing attitudes of anger, attachment, and so on. These disturbing attitudes motivate our actions, which in turn leave karmic imprints on our mindstreams. When these imprints ripen, we meet with suffering.
--from Transforming Adversity into Joy and Courage: An Explanation of the Thirty-seven Practices of Bodhisattvas by Geshe Jampa Tegchok

Let us start practicing meditation

If you continue to practice meditation, then your experience will gradually increase and there will be greater and greater stability and greater and greater lucidity. However, the experiences that can arise in meditation can take various different forms. And in spite of the fact that the person has a real recognition of the mind's nature, there is still the possibility or probability of fluctuation in experience even after that.
Sometimes you may feel that you have amazing, tremendous meditation, and at other times you may feel that you have no meditation at all. This characterizes meditation experience, which fluctuates a great deal. Realization, which is distinct from experience, does not change, but experiences can fluctuate a great deal or alternate between good and bad. There will still be times when you will have what you regard as good experiences and, in contrast, what you regard as bad experiences. When that occurs, just keep on looking. Don't get distracted or sidetracked by the experience. Whatever meditation experience arises, you should recognize that it is transitory. As is said, "meditation experience is like mist, it will surely vanish."
Experiences are different from the actual fact of the recognition itself. Because they are ephemeral experiences, they aren't worth investing in. So if you have a bad meditation experience, do not be alarmed, because it too will vanish. If you have a good meditation experience, you need to continue; if you have a bad meditation experience, you need to continue. In either case, you simply need to continue to rest in this recognition of the mind's nature.
--from Pointing Out the Dharmakaya by Khenchen Thrangu Rinpoche, foreword by the Dalai Lama

The Physical World & the World of Mental Phenomena

The essential point about this condition of potentiality is that, although there is a causal relationship between the physical world and the world of mental phenomena, in terms of their own continuum one cannot be said to be the cause of the other. A mental phenomenon, such as a thought or an emotion, must come from a preceding mental phenomenon; likewise, a particle of matter must come from a preceding particle of matter.
Of course, there is an intimate relationship between the two. We know that mental states can influence material phenomena, such as the body; and, similarly, that material phenomena can act as contributory factors for certain subjective experiences. This is something that we can observe in our lives. Much of our gross level of consciousness is very closely connected to our body, and in fact we often use terminology and conventions which reflect this.
For example, when we say 'human mind' or 'human consciousness' we are using the human body as the basis to define a particular mind state. Likewise, at the gross levels of mind such as our sensory experiences, it is very obvious that these are heavily dependent upon our body and some physiological states. When a part of our body is hurt or damaged, for instance, we immediately experience the impact on our mental state. Nevertheless, the principle remains that mental phenomena must come from preceding phenomena of the same kind, and so on.
If we trace mental phenomena back far enough, as in the case of an individual's life, we come to the first instant of consciousness in this life. Once we have traced its continuum to this point of beginning, we then have three options: we can either say that the first instant of consciousness in this life must come from a preceding instant of consciousness which existed in the previous life. Or we can say that this first instant of consciousness came from nowhere--it just sort of 'popped up'. Or we can say that it came from a material cause.
From the Buddhist point of view, the last two alternatives are deeply problematic. The Buddhist understanding is that, in terms of its continuum, consciousness or mind is beginningless. Mental phenomena are beginningless. Therefore, the person or the being--which is essentially a designation based on the continuum of the mind--is also devoid of beginning.
--from Lighting the Way by the Dalai Lama, translated by Geshe Thupten Jinpa

Anger Only Harm Us

People harm others only when they are unhappy. No one wakes up in the morning and says, "I feel so great today! I think I'll go out and harm someone!" When we can allow ourselves to know the depth of the pain and confusion felt by those who have harmed us, compassion--the wish that they be free from such suffering--can easily arise. Thinking in this way does not mean whitewashing or denying harm that was done. Rather, we acknowledge it, but go beyond amassing resentment, because we know that grudges help neither ourselves nor others.
--from Working with Anger by Thubten Chodron

Kind Qualities of Our Chosen Guru

The reason why the qualities of a teacher are described at such length in the scriptures is because we should know what to look for when seeking a guru capable of opening up the Buddhist paths within us. To take up training under an unqualified teacher can be disastrous. It is said in the tantric scriptures that one is not unwise to examine a guru for twelve years before accepting that person as one's teacher. The choice of teachers is an important one and must be made carefully.
Not only does the guru perform the work of the Buddhas and thus equal them in activity, in terms of kindness the guru surpasses them. Of all Buddhas of the past who have manifested as universal teachers, it is said that Buddha Shakyamuni is kindest to us; for it is with his teachings that we have come into contact...even though Buddha Shakyamuni is most kind of the past Buddhas, still we are unable to receive teachings from him or witness his inspiring presence.
Were all the Buddhas and lineage masters of the past to manifest before us at this very moment, we would not be able to recognize them as enlightened beings. Due to our not having a sufficiently strong karmic connection with them, they would be unable to affect us. The guru performs the great kindness of coming to us in an ordinary form which we can perceive and to which we can relate, and carries out the work of the Buddhas in our lives. The fact that a donkey like us is brought into the family of spiritual beings is purely due to the kindness of the guru. The Buddhas can only come to us through him or her. Thus if we do not respect the guru and heed his or her teachings, what hope do we have? We should meditate upon the guru's unexcelled kindness and give birth to profound appreciation.
The reason why we have been wandering unceasingly in cyclic existence since time immemorial is because we have not met a spiritual master before; or even if we have met one we did not cultivate an effective relationship with him or her. We should determine to take the opportunities afforded by our present human situation and cultivate a spiritual practice under the guidance of a master.
--from The Path to Enlightenment by H.H. the Dalai Lama, edited and translated by Glenn H. Mullin,

You Can Tell Yourself Who You Are

We are all persons who have accumulated misdeeds in the past. This is indicated by the fact that at present bad thoughts constantly rise up in our minds, thereby showing that in the past for a long period we have become excessively used to these bad thoughts. In this way it is said that you can tell what you were doing in the past by examining your body now and that you can tell what will come in the future by looking at what you are doing with your mind now.
In any case, with regard to whatever misdeeds have been done in the past, you should engage in disclosure of them and in developing an intention to restrain from them in the future. For a Buddhist practitioner, the usual practices include prostration and recitation of certain mantras such as the one hundred syllable mantra. One of the best methods is to make gifts to poor and sick persons. The giving of donations for education as well as in the medical field is very great work, one of the best ways to gain merit.
--from The Dalai Lama at Harvard: Lectures on the Buddhist Path to Peace