from The Essence of the Heart Sutra by Tenzin Gayatso, the 14th Dalai Lama.
The great Indian masters of Nalanda Monastery set out two principal methods for generating bodhichitta: the seven-point cause-and-effect method and the method of equalizing and exchanging self and others.
In the seven-point cause-and-effect method, you visualize every being as your own beloved mother or as another person for whom you have the utmost affection—someone who for you embodies great kindness. To practice this aspect of the method, call up the feelings of affection that arise with regard to one’s mother or another maternally kind and loving person and then extend those feelings to every other being, perceiving that each being has been equally kind and loving to you. When we truly realize our interconnectedness over the scope of beginningless lifetimes, we realize that every other being has been our parent and has treated us with this same loving and nurturing kindness.