In giving we not only find wealth while in cyclic existence but we achieve the zenith of prosperity in supreme enlightenment. Therefore we all have to practice giving. A Bodhisattva's giving is not just overcoming miserliness and being generous to others; a pure wish to give is cultivated, and through developing more and more intimacy with it, such giving is enhanced infinitely. Therefore it is essential to have the firm mind of enlightenment rooted in great love and compassion and, from the depths of one's heart, to either give one's body, wealth and virtues literally to sentient beings as infinite as space, or to dedicate one's body, wealth and virtues for them while striving in all possible ways to enhance the wish to give infinitely. As mentioned in Engaging in Bodhisattva Activities and in The Precious Garland, we should literally give material help to the poor and needy, give teaching to others, and give protection to them, even the small insects, as much as we can. In the case of things which we are not able to part with, we should cultivate the wish to give them away and develop more and more intimacy with that wish.
From Generous Wisdom

There is a Buddhist practice in which one imagines giving joy and the source of all joy to other people, thereby removing all their suffering. Though of course we cannot change their situation, I do feel that in some cases, through a genuine sense of caring and compassion, through our sharing in their plight, our attitude can help alleviate their suffering, if only mentally. However, the main point of this practice is to increase our inner strength and courage.
I have chosen a few lines that I feel would be acceptable to people of all faiths, and even to those with no spiritual belief. When reading these lines, if you are a religious practitioner, you can reflect upon the divine form that you worship. Then, while reciting these verses, make the commitment to enhance your spiritual values. If you are not religious, you can reflect upon the fact that, fundamentally, all beings are equal to you in their wish for happiness and their desire to overcome suffering. Recognizing this, you make a pledge to develop a good heart. It is most important that we have a warm heart. As long as we are part of human society, it is very important to be a kind, warm-hearted person.
May the poor find wealth,
Those weak with sorrow find joy.
May the forlorn find new hope,
Constant happiness and prosperity.

May the frightened cease to be afraid,
And those bound be free.
May the weak find power,
And may their hearts join in friendship.
from An Open Heart: Practicing Compassion in Everyday Life

Patiently accepting small hardships gives one the opportunity to apply other practices. One could make aspirational prayers and the dedication, "By my experience of this suffering, may I be able to purify my negativities committed in the past." One can also use the opportunity for the practice of tong-len, which is the Mahayana practice of "giving and taking."
...This advice is especially useful when dealing with illnesses. Of course it is important, first of all, to take all the preventative measures so one does not suffer from illnesses, such as adopting the right diet, or whatever it may be. Then when one becomes ill, it is important not to overlook the necessity for taking the appropriate medications and other measures necessary for healing. However, there would be an important difference in how one responded to illness if instead of moaning about the situation, instead of feeling sorry for oneself, instead of being overwhelmed by anxiety and worry, one saved oneself from these unnecessary additional mental pains and suffering by adopting the right attitude. Although it may not succeed in alleviating the real physical pain and suffering, one can think, "May I, by experiencing this pain and suffering, be able to help other people and save others who may have to go through the same experience." One can in this way use that opportunity for a spiritual practice, in other words, practicing tong-len meditation, or "giving and taking." This type of practice, although it might not necessarily lead to a real cure in physical terms, can definitely protect one from unnecessary additional mental suffering and pain. And on top of that, it is also possible that instead of being saddened by the experience one can see it as a kind of privilege. One can see it as an opportunity and in fact be joyful because of this particular experience which has made one's life richer.
Healing Anger: The Power of Patience from a Buddhist Perspective

Whatever joy there is in this world
All comes from desiring others to be happy,
And whatever suffering there is in this world
All comes from desiring myself to be happy.

If I do not actually exchange my happiness
For the sufferings of others,
I shall not attain the state of Buddhahood
And even in cyclic existence I shall have no joy.

The holy secret of the practice of Tonglen is one that the mystic masters and saints of every tradition know; and living it and embodying it, with the abandon and fervor of true wisdom and true compassion, is what fills their lives with joy. One modern figure who has dedicated her life to serving the sick and dying and who radiates this joy of giving and receiving is Mother Teresa. I know of no more inspiring statement of the spiritual essence of Tonglen than these words of hers:
We all long for heaven where God is, but we have it in our power to be in heaven with Him at this very moment. But being happy with Him now means:
Loving as He loves,
Helping as He helps,
Giving as He gives,
Serving as He serves,
Rescuing as He rescues,
Being with Him twenty-four hours,
Touching Him in his distressing disguise.

One of the greatest masters of Tonglen in Tibet was Geshe Chekhawa, who lived in the eleventh century. He was extremely learned and accomplished in many forms of meditation. One day when he happened to be in his teacher’s room, he came across a book lying open at the following lines:
Give all profit and gain to others,
Take all loss and defeat on yourself.
The vast and almost unimaginable compassion of these lines astounded him and he set out to find the master who had written them. One day on his journey he met a leper who told him that this master had died. But Geshe Chekhawa persevered and his long efforts were rewarded when he found the dead master’s principal disciple. Geshe Chekhawa asked this disciple: “Just how important do you think the teachings contained in these two lines are?” The disciple replied: “Whether you like it or not, you will have to practice this teaching if you truly wish to attain buddhahood.”

When someone is suffering and you find yourself at a loss to know how to help, put yourself unflinchingly in his or her place. Imagine as vividly as possible what you would be going through if you were suffering the same pain. Ask yourself: “How would I feel? How would I want my friends to treat me? What would I most want from them?”
When you exchange yourself for others in this way, you are directly transferring your cherishing from its usual object, yourself, to other beings. So exchanging yourself for others is a very powerful way of loosening the hold on you of the self-cherishing and the self-grasping of ego, and so of releasing the heart of your compassion.

Visualize someone to whom you feel very close, particularly someone who is suffering and in pain. As you breathe in, imagine you take in all their suffering and pain with compassion, and as you breathe out, send your warmth, healing, love, joy, and happiness streaming out to them.
Now, gradually widen the circle of your compassion to embrace first other people to whom you also feel very close, then to those about whom you feel indifferent, then to those whom you dislike or have difficulty with, then even to those whom you feel are actively monstrous and cruel. Allow your compassion to become universal, and to enfold in its embrace all sentient beings, and all beings, in fact, without any exception.

Compassion is the best protection; it is also, as the great masters of the past have always known, the source of all healing. Suppose you have a disease such as cancer or AIDS. By taking on the sickness of those suffering like you, in addition to your own pain, with a mind full of compassion, you will—beyond any doubt—purify the past negative karma that is the cause, now and in the future, of the continuation of your suffering.
In Tibet there have been many extraordinary cases of people who, when they heard they were dying of a terminal illness, gave away everything they had and went to the cemetery to die. There they practiced taking on the suffering of others; and what is amazing is that instead of dying, they returned home, fully healed.

I know very well from my own experience how hard it is to imagine taking on the sufferings of others, and especially those of sick and dying people, without first building in yourself a strength and confidence of compassion. It is this strength and this confidence that will give your practice the power to transmute the suffering of others.
This is why I always recommend that you begin the Tonglen practice for others by first practicing it on yourself. Before you can send out love and compassion to others, you must uncover, deepen, create, and strengthen them in yourself, and heal yourself of any reticence or distress or anger or fear that might create an obstacle to practicing Tonglen wholeheartedly.

Of all the practices I know, the practice of Tonglen, Tibetan for “giving and receiving,” is one of the most useful and powerful. When you feel yourself locked in upon yourself, Tonglen opens you to the truth of the suffering of others; when your heart is blocked, it destroys those forces that are obstructing it; and when you feel estranged from the person who is in pain before you, or bitter or despairing, it helps you to find within yourself and then to reveal the loving, expansive radiance of your own true nature. No other practice I know is as effective in destroying the self-grasping, self-cherishing, self-absorption of the ego, which is the root of all our suffering and all hard-heartedness.
Put very simply, the Tonglen practice of giving and receiving is to take on the suffering and pain of others and give to them your happiness, well-being, and peace of mind.