What you fear most tends to happen; your anxieties often materialize.
他总是担心自己会犯错，结果越是小心翼翼，越是容易出差错，真是怕处有鬼啊。
He always worried about making mistakes, and the more cautious he became, the more prone he was to errors. It's truly a case of 'what you fear most tends to happen'.
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