If you want others to be happy, practice compassion. If you want to be happy, practice compassion.
~ The Dalai Lama 
Slogan 7- Sending and taking should be practiced alternately. These two should ride the breath
Slogan 10 – Begin the sequence of sending and taking with yourself.
(… It is impossible to be truly compassionate, receive another’s pain, if you are unable to receive your own. Norman Fischer.)
Norman Fischer from Training in Compassion
“…The practice of sending and receiving has two main purposes: first, to train your heart to do what it usually does not want to do: to go toward, rather than away from, was painful and difficult in your own life; and second, to realize that your own suffering and the suffering of others are not different…
“Sending and receiving begins and ends with the absolute bodhicitta slogan Rest in the openness of mind. It is this comforting and supportive resting that gives us the basis we need for the hard work that the practice entails. In the beginning we gather courage from it, and in the end we return to it for rest and recuperation. 
“Start by breathing in the openness of mind that you can feel in the clarity and strength of the inhale. And then exhale, letting go completely and merging with openness of mind, so that there is nothing else present but that. Breathing this way, we open to a complete release of everything and trust of everything, especially when we exhale, resting in the natural openness of our own being and of everything. In a way, there is nothing at all to this. It’s no big deal. It’s not colorful, if not spectacular, it’s not profound or special. It’s just and easeful opening and letting go. It feels as if we’re floating, buoyed up by the waters of reality. That’s how we begin the practice, staying with this part as long as we need to.
“Next, we practice sending and receiving, as the slogan says: practice them alternately; they should ride the breath. So the next time we breathe in, we breathe in our own pain and suffering. Not only do we not avoid it as we usually do, as it is our natural impulse to do, we actually breathe it into our body. We gobble up all the suffering and pain. We may well be squeamish about this, and it might be difficult at first, but with practice we can do it. We can visualize the pain and suffering as a dark, sticky substance or smoke or some kind of goo that we are breathing in, taking into our bodies. The goo is coming from all around us, and we are taking it in, with all the pores of our body as well as through our nostrils as we breathe in. If you are not so visually oriented and this image of goo is not useful, then in some other way imagine you are actually breathing in the pain and suffering, really taking it in. This is receiving.
“Of course, we don’t only breathe in, we also breathe out. When we breathe out, something miraculous happens. It turns out that our bodies are transformation machines. They transform the goo, the suffering, pain, into lightness, ease, peacefulness that comes out of our nostrils and all the pores of our body as a light, sweet mist (or if you are not visually oriented, as a more imaginative and vague sense of lightness and ease, maybe even joy). Unharmed by the pain we breathed in, we have now transformed that pain so that we now breathe out bliss and ease and lightness and healing power, as if we were breathing out, healing light. This is sending. We are sending healing light to ourselves and to many others.”
Alan Wallace from Buddhism with an Attitude
“…The practice of giving and taking, tonglen, uses the power of imagination to engage with realities beyond immediate experience. The enactment of loving-kindness is the “giving” component of the practice of giving and taking, and the enactment of compassion is the “taking” component. The taking component begins by bringing to mind as vividly as you can a loved one or a community of people whom you care about deeply and who is suffering. The cause of the suffering may be physical, psychological, social or environmental. For the moment, empathetically enter into the suffering of this person or group. Imagine experiencing the burden of their adversity. Now, in your mind’s eye, stand back and bring forth the wish, “May you be relieved of this burden and may this adversity ripen upon me.” Whatever the affliction or adversity, physical or mental, imagine taking from this person the despair, affliction, and pain. Imagine 
the suffering in the form of a black cloud being removed from the other person’s body and mind and being drawn into your heart. Imagine that as the suffering is funneled into your heart, that person is gradually relieved. As soon as this dark cloud enters your heart, imagine that it meets with your own sense of self-centeredness, visualized as an orb of darkness, and that in an instant both that cloud of misery and your self-centeredness mutually extinguish each other, leaving not a trace of either behind. Now imagine all of your merit, prosperity, happiness, all the blessings in your life from the past, present and future, as a powerful wellspring of brilliant white light emanating from your heart in the reverse direction. Imagine these powerful rays of light reaching out suffusing the person with the prayer, “All that is good in my life, my possessions, my happiness, my good health, my virtues, of the past, present and future, I offer to you. May you be well and happy. May your greatest yearnings and deepest aspirations be fulfilled.” Imagine that the light of virtue and happiness begins to suffuse the people you have brought to mind and imagine their most meaningful desires and aspirations being fulfilled. Yet as this light from your heart flows forth unimpededly, it is not depleted from its inexhaustible source”
Wallace then repeats the process with “a person or group who is deluded and acts in ways harmful to themselves and others.” He then expands “to take in all suffering and mental afflictions and send forth all your virtue and goodness.”
Pema Chodron from Start Where you Are
“…Tonglen practice has four stages. The first stage is flashing openness, or flashing absolute bodhicitta. The slogan “Rest in the nature of alaya, the essence” goes along with this flash of openness, which is done very quickly. There is some sort of natural flash of silence and space. It’s a very simple thing.
“The second stage is working with the texture. You visualize breathing in dark, heavy, and hot and breathing out white, light, and cool. The idea is that you are always breathing in the same thing: you are essentially breathing in the cause of suffering, the origin of suffering, which is fixation, the tendency to hold on to ego with a vengeance.
“…You may have noticed times when you are all caught up in yourself, and then some sort of contrast or gap occurs. It’s very spacious. That’s the experience of mind that is not fixated on phenomena; it’s the experience of openness. The texture of that openness is generally experienced as light, white, fresh, clear, and cool.
“…in the second stage of tonglen you work with those textures. You breathe in black, heavy, and hot through all the pores of your body, and you radiate out white, light, and cool, also through all the pores of your body, 360 degrees. You work with the texture until you feel that is synchronized: black is coming in and white is going out on the medium of the breath – in and out, in and out.
“The third stage is working with a specific heartfelt object of suffering. You breathe in the pain of a specific person or animal that you wish to help. You breathe out to that person spaciousness or kindness or a good meal or cup of coffee – whatever you feel would lighten their load. You can do this for anyone: the homeless mother that you pass on the street, your suicidal uncle, or yourself and the pain you are feeling at that very moment. The main point is that the suffering real, totally untheoretical. It should be heartfelt, tangible, honest, and vivid.
“The fourth stage extends this wish to relieve suffering much further. You start with the homeless person and then extend out to all those who are suffering just as she is, or to all those who are suicidal like your uncle or to all those who are feeling the jealousy or addiction or contempt that you are feeling. You use specific instances of misery as a stepping stone for understanding the universal suffering of people and animals everywhere. Simultaneously, you breathe in the pain of your uncle and of all the zillions of other desperate, lonely people like him. Simultaneously, you send out spaciousness or cheerfulness or a bunch of flowers, whatever would be healing, to your uncle and all the others. What you feel for one person, you can extend to all people.
“You need to work with both the third and fourth stages – with both the immediate suffering of one person and the universal suffering of all. If you were only to extend out to all sentient beings, the practice would be very theoretical. It would never actually touch your heart. On the other hand, if you were to work only with your own or someone else’s fixation, it would lack vision. It would be too narrow. Working with both situations together makes the practice real and heartfelt; at the same time, it provides vision and way for you to work with everyone else in the world.
“You can bring all of your unfinished karmic business right into the practice. In fact, you should invite it in. Suppose that you are involved in a horrific relationship: every time you think of a particular person you get furious. That is very useful for tonglen! Or perhaps you feel depressed. It was all you could do to get out of bed today. You’re so depressed that you want to stay in bed for the rest of your life; you have considered hiding under your bed. That is very useful for tonglen practice. The specific fixation should be real just like that.”
Here’s a link to Pema Chodron talking about Tonglen: https://vimeo.com/shambhala/review/161255998/424412f6b6
opencirclemindfulness.org 