The remark expresses Santiago’s belief that strength can be created through conduct as well as possessed in advance. He imagines the marlin judging him as stronger and more capable than he may actually feel, and resolves to live up to that impression. Confidence therefore becomes a form of commitment: by acting as though he has greater endurance, he may discover or develop the strength required.

In The Old Man and the Sea, this thought reflects Santiago’s struggle against exhaustion, pain and age during his contest with the marlin. His physical limitations are real, but he refuses to let them entirely determine his behaviour. The line suggests that identity is partly shaped by what a person repeatedly chooses to do under pressure. It does not claim that belief can remove every limitation; rather, it presents self-belief as a means of extending effort when circumstances demand more than someone thinks they can give.