self-fulfilling prophecy = 自我实现的预言
The act of making a prophecy, would help making it happen.
Some prophecy fulfilling itself by enticing actions that lead to the result that it predicted. For example: Someone say he will never success, therefore no need to try. If he never try, he will never success. And the reason he never try is he predicted it would be no use trying. If he didn't make the prediction, he might actually try and success
"I will never succeed" is a self-fulfilling prophecy, because if you believe in this prophecy, you will not try. If you don't try, this prophecy will come true.
You are the one who fulfill your own prophecy
In Mandarin, you can say: "說着就會變真" (keep making the same prediction would make this prediction come true)
In Cantonese, you can say: "講講下就會變真"
"說到變真" (repeat a prediction until it comes true) could work similarly to "說着就會變真" (keep making the same prediction would make this prediction come true)
For example: "他常說沒人會嫁他，結果這話說到變真" (he often say no one would marry him, at the end this words became a self-fulfilling prophecy)
Because he predicted no girl would marry him, so he didn't even try to ask girls for marriage, thus fulfilled his own prophecy