source of vitality; life sustenance
A set phrase meaning something that gives one the energy or motivation to live; often used metaphorically for emotional or spiritual nourishment.
See also: 糧 (かて)
For him, music is what keeps him going.
Reading has become my source of vitality.
Compound of 生きる (to live) and 糧 (sustenance, food). The exact historical derivation is uncertain, but the phrase is conventionally used to mean something that sustains one's life or spirit.