Taylor Swift lives in constant fear of ruining her glittering career so she makes an extra effort not to "mess up" or become "complacent" and "mouthy".

The country star admits her global success feels like a dream and she worries it won't last.

She tells Vogue magazine, "This is what I've wanted to do my whole life. It never freaks me out. Never. Ever. But you know what does freak me out? When is the other shoe going to drop? I am so happy right now. So I am always living in fear. This can't be real, right? This can't really be my life."

However, the Love Story hitmaker is determined to keep progressing with her career by not letting fame go to her head.

She adds, "The stakes are really high if you mess up, if you slack off and don't make a good record, if you make mistakes based on the idea that you are larger than life and you can just coast. If you start thinking you've got it down, that's when you run into trouble - either by getting complacent or becoming mouthy. And nobody likes that."