The practice of sending and receiving is called tonglen in Tibetan Buddhism. The word tonglen combines tong, which means sending out, with len which means receiving.
Practiced as a Meditation
Chögyam Trungpa teaches the practice of sending and receiving as a sitting meditation. Here is how he describes sending and receiving meditation in his book Training the Mind & Cultivating Loving-Kindness.
The practice of tonglen is quite straightforward; it is an actual sitting meditation practice. You give away your happiness, your pleasure, anything that feels good. All of that goes out with the outbreath. As you breathe in, you breathe in any resentments and problems, anything that feels bad. …We do not first have to sort out our doctrinal definitions of goodness and evil. We simply breathe out any old good and breathe in any old bad.

