Garnica was born August 25, 1978 in Granada, Spain. His father was a police officer. While born in Granada, his family moved to Valencia when he was a baby. His parents learned about his eye sight problem when he was two years old. Doctors learned he had retinitis pigmentosa, an eye disease that means he sees worse over time. When he was a nine-year-old, he learned to read using braille after his eyesight got worse. He played basketball and handball when he was a boy.