Reading is a pleasure of the mind, which means that it is a little like a sport: your eagerness and knowledge and quickness make you a good reader. Reading is fun, not because the writer is telling you something, but because it makes your mind work. Your own imagination works along with the author's or even goes beyond his. Your experience, compared with his, brings you to the same or different conclusions, and your ideas develop as you understand his.
Every book stands by itself, like a one-family house, but books in a library are like houses in a city. Although they are separate, together they all add up to something; they are connected with each other and with other cities. The same ideas, or related ones, turn up in different places; the human problems that repeat themselves in life repeat themselves in literature, but with different solutions according to different writings at different times.
Reading can only be fun if you expect it to be. If you concentrate on books somebody tells you "ought" to read, you probably won't have fun. But if you put down a book you don't like and try another till you find one that means something to you, and then relax with it, you will almost certainly have a good time--and if you become as a result of reading, better, wiser, kinder, or more gentle, you won't have suffered during the process.