Shark attack survivor Leah Stewart has described the moment "a left hook" punch and her sheer will to watch her daughter grow up saved her life.

Leah Stewart has opened up about the terrifying moment she realised she was 30cm from a 'monster' shark at Sydney's Coogee Beach.

Sydney woman Leah Stewart recounts her harrowing tale of survival on 60 Minutes after losing her arm in a shark attack.