Courage does not wait for the odds to feel fair.
The odds are not secretly even. Goliath is presented as a seasoned, heavily armed champion. David is young, carries no armor, and is initially there to deliver food to his brothers. Saul's objection is practical, not absurd: David does not look equipped for single combat.
The text never says David feels no fear. It shows something more useful than a report of his feelings. He speaks up, offers himself, and walks into the valley. Courage may include fear, doubt, or a racing body. It is visible in the choice not to let those things make every decision.
Past action can give present courage a grip.
When Saul questions him, David does not claim to be naturally fearless. He points to work he has already done: guarding sheep from predators. Those experiences do not make Goliath small. They give David evidence that he has met danger before and acted effectively.
He also refuses armor that does not fit his experience. David takes his staff, sling, and stones instead. This is not a general rule against help, planning, or training. It is a picture of someone identifying the tools he can actually use, rather than performing competence in someone else's equipment.
Conviction can make action possible without making it safe.
David frames the confrontation in terms larger than his own reputation. He says Goliath has defied Israel's God, and he trusts that the outcome is not decided by sword and spear. Whatever a reader makes of that belief, it gives his action a frame that is not merely self-display.
That conviction does not remove risk or guarantee a repeatable formula. The story's outcome is swift, but the choice comes before the outcome is known. Courage is not confidence that nothing can go wrong. It is a willingness to take responsibility for a necessary act when safety cannot be promised.