Alice laughed. `There's no use trying,' she said `one can't believe impossible things.'`I daresay you haven't had much practice,' said the Queen. `When I was your age, I always did it for half-an-hour a day. Why, sometimes I've believed as many as six impossible things before breakfast.
This is one of my very favorite quotes, from one of my very favorite stories. No CGI or 3D required for imagining impossible things :)