Miranda Kerr "can't believe" she's still modelling.

Speaking during an appearance as a guest judge on Australia’s Next Top Model, she said: "Inevitably, rejection is going to happen in this career. I’ve had so much rejection myself, and it’s because I didn’t take it personally and I just had fun with it; that is why I feel I’ve continued my career as long as I have.

"I never ever envisioned that it would last this long. I can’t believe I am modelling 20 years later; it is kind of wild really."

Meanwhile, Miranda - who has five-year-old son Flynn with ex-husband Orlando Bloom - previously revealed her grandmother is her fashion muse.

She said: "It's crazy. My grandmother really influenced me a lot. My first dress I fell in love with was this beautiful blue velvet dress of hers and I used to dress up and walk around the house in it.

"She used to get all of her pieces tailored, it wasn't about having expensive pieces, because we grew up not really having too much, but she always looked so beautifully put together. She would be in the kitchen baking a cake and looked so chic. [And] I like to invest in classic pieces, I like to tailor pieces and I like a little bit of a twist, something that can be unexpected. I'm a little old fashioned."

And Miranda also revealed she changes her style depending on the city she's in.

She added: "In New York I feel like anything goes. In LA, it's definitely a lot more casual. In New York, I love to dress up for the winter season and really embrace the layers and have over-the-knee boots, where if I wore that in Malibu, people would think I was crazy.

"So in Malibu I try to keep it really simple. I honestly wear a lot of tights and sneakers. Australia is also very quite relaxed - kind of like the Malibu vibe - depending on if I have a business meeting."