We now know that you can't train yourself out of a bad habit through sheer willpower (which is why so many diets fail). But we also know that the brain is a plastic thing, and perception is malleable.
As both patient and scientist, Sue Barry offers insight into the condition of strabismus, which caused her to see the world in 2-D from the age of 2 to the age of 48. In college, while studying neurobiology, she was told that the wiring of the brain is fixed after a specific window of time early in one's development. She believed she'd never be able to in three dimensions. She tried anyway, and her experience taught her that what she'd thought was a biological lost cause was actually a habit of the mind.
There are good evolutionary reasons for habits, argues Charles Duhigg, an investigative journalist. Habits save us time and mental energy in negotiating the world, and free our minds to invent things like fire and computers. They also limit the size of our brains (and therefore our heads), making it easier for human mothers to survive the act of giving birth. The best strategy is not to try to eradicate them entirely, but to redirect them.