That's what reading as an adult is: to be so caught up in reading and writing, so conscious of each as work made up of skills that must be honed, so dedicated to continuing to do so across one's life, that one can take up any text and knowledgeably discuss its structure as well as its content, and place both in comparative perspective. This is not reading as it is conventionally thought of or discussed. Reading is usually the skill children put together around the age of five: recognizing letters, sounds, putting those together into words, putting words into sentences, and then recognizing the way in which those sentences can pass along information or construct a story. Instruction in reading, prior to college, is usually restricted to bringing in a number of basic literary categories: simile and metaphor, motif, theme, symbolism, and, given the likelihood of a high school reading curriculum running into some problems of antiquated views on race, gender, etc, some idea of how to situate a book in its historical context. On writing there is virtually no instruction at all: the best high school graduates come into the finest universities with little ability to do more than compose a five-paragraph essay, which is simply a robotic exercise in fitting content into an indifferent mould. The idea that an introductory paragraph has specific work to do--the idea that the 17th paragraph needs to have specific work to do--is a concept that can take the best part of a year to master, and much longer to produce. The average college student does not read, apart from assignments (sometimes not even then), and writes only the minimum required, and therefore struggles to do either.
Reading like an adult is like so many other adult things: a skill, and one that can only be learned through constant action and continual reinforcement. If one periodically cooks a number of unrelated dishes, cooking will seem like a difficult and unpleasant skill; the more practice one gets, and the more closely related the things one chooses to make, the more it becomes a series of easy and repeatable actions. (I can still remember when I looked at Fuchsia Dunlop's Land of Plenty and realized that the sauces were just different balances of types of flavor, and that there were only three or four different preparations, which varied only by vegetables and proteins used; it's now faster for me to chop onions and garlic, or other vegetables, than to use a mandoline or food processor.) Reading makes it easier to identify plot structure, and writing makes it easier to see why particular writers affect and others leave one cold; they make it clear not just that something has transcended the realm of what others can do, but why; reading and writing make it easier to produce those effects in others. As with all those other adult skills, though, one can do without them, but it's hard not to see something missing without them.