There is a discipline that a lot of people that hold themselves out to be UX professionals have never heard of. it is called Human Factors and is a subset of industrial psychology.

If a person has never read a book on Human Factor theory, they are not a UX professional they are a design hack.

Human Factors focuses on what the mind wants to do rather than individual opinions of how one thinks it should work. There are years of scientific method based research in Human Factors studies that is willfully or ignorantly ignored by the web design community.

If you want to be great you need to ground yourself in Human Factors as well as aesthetic design. They are different disciplines and both are important to user experience. As well a subset of human factors specifically focused on computing is HCI, while you can short cut and just read HCI related info, there is a wealth of info that can be drawn upon from other elements of Human Factors such as product design, and ergonomics while not directly related the theories can be adapted to UI usability.