Work on taking and sending with these considerations in mind:
In general, all methods for attaining buddhahood rely on sentient beings. Therefore, to the individual who wishes to awaken, sentient beings are as worthy of gratitude as buddhas. Specifically, all sentient beings are worthy of gratitude since there is not one who has not been my parent. In particular, all those who hurt me are worthy of gratitude since they are my companions and helpers for gathering the accumulations of merit and pristine wisdom and for clearing away the obscurations of disturbing emotions and conceptual knowledge.
Do not be angry, not even at a dog or an insect. Strive to give whatever actual help you can. If you cannot help, then think and say:
May this sentient being (or troublemaker) quickly be rid of pain and enjoy happiness. May he come to attain buddhahood.
From now on, all the virtuous acts I do shall be for his welfare.
When a god or a demon troubles you, think:
This trouble now occurs because I, from time without beginning, have made trouble for him. Now I shall give him my flesh and blood in recompense.
Imagine the one who troubles you to be present in front of you and mentally give him your body as you say:
Here, revel in my flesh and blood and whatever else you want.
Meditate with complete conviction that this troublemaker enjoys your flesh and blood, and is filled with pure happiness, and arouse the two kinds of bodhicitta in your mind. Or:
Because I had let mindfulness and other remedies lapse, disturbing emotions arose without my noticing them. Since this troublemaker has now warned me of this, he is certainly an expression of my guru or a buddha. I'm very grateful to him because he has stimulated me to train in bodhicitta.
Or, when illness or suffering comes, think with complete sincerity:
If this hadn't happened, I would have been distracted by materialistic involvements and would not have maintained mindfulness of dharma. Since this has brought dharma to my attention again, it is the guru's or the jewels' activity, and I am very grateful.
To sum up, whoever thinks and acts out of a concern to achieve his or her own well-being is a worldly person; whoever thinks and acts out of a concern to achieve the well-being of others is a dharma person. Langri-tangpa has said:
I open to you as deep a teaching as there is. Pay attention! All faults are our own. All good qualities Are the lords', sentient beings. The point here is: give gain and victory to others, take loss and defeat for ourselves. Other than this, there is nothing to understand.
From The Great Path of Awakening : An Easily Accessible Introduction for Ordinary People by Jamgon Kongtrul, translated by Ken McLeod. Copyright 1993 by Ken McLeod.
Published by arrangement with Shambhala Publications, Inc., Boston.
This site provides an on-line database of commentaries on the Tibetan Buddhist meditation practices of lojong (Mind Training) and tonglen.