Subject[Hemingway] The Snows of Kilimanjaro

"You're not going to die."

"Don't be silly. I'm dying now. Ask those bastards." He looked over to where the huge,
filthy birds sat, their naked heads sunk in the hunched feathers. A fourth planed down, to
run quick-legged and then waddle slowly toward the others.

"They are around every camp. You never notice them. You can't die if you don't give up."

"Where did you read that? You're such a bloody fool."

(1) "You might think about some one else."

"For Christ's sake," he said, (2) "that's been my trade."

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I have two questions. Please help.

What's the meaning of sentence (1)? I understood like this : "I'm not a fool. Perhaps (possibly) you think and are talking about another person than me.” Am I right?

And the sentence (2) is more tricky. What does mean ‘trade’?