...referring to the Kabala, in which every mitzvah (good deed) people perform creates an 'angel'. Those angels don't vanish with the acts that brought them into being but live on, affecting the balance between good and evil.
Source: Tales of Wonder: Adventures Chasing the Divine, an Autobiography
When one begins to purposefully perform acts of kindness, the spirit changes and soon doing good deeds becomes a focal point for our life; doing good begins to be the same as feeling good. The periods of emptiness when we search for the "meaning of it all" begin to fill with acts of kindness.