While it's best (and easiest) to encourage a love of books in children when they're little, it's never too late, and it's always worth the effort. Of course, you'll need to use different strategies, but the goal is the same: to build a connection between feelings of well-being, security, and happiness and reading. Unfortunately, as kids get older, they start to associate reading with negative things (studying for a test, doing homework) and negative feelings (anxiety, stress). What you want to do is turn that around, so reading is seen as something relaxing and pleasurable.
I suggest you set aside an hour each night after dinner for reading. The TV is off as well as cell phones and computers. Your family gathers in a cozy room, and everybody reads something of their choice (a novel, magazines, comic books, non-fiction), but nothing work or school related. To make it more enjoyable, serve hot cocoa, popcorn, and dessert from time to time. During the last 10 minutes, have everyone share something about what they read. If this sounds impossible to do because your family is too busy on weekdays, do it just one night a week—perhaps, Friday or Saturday--when everyone isn't so frantic with after school activities and homework.
Also, make sure you and your spouse are setting a good example by reading often for pleasure. At dinner time, talk about what you're reading and why you're enjoying it. Discuss different genres and authors. Elevate the dinner conversation by discussing literature, not just the latest TV shows and movies.
When my sons were in middle school, they loved participating in the “Battle of the Books,” a nation-wide program to promote reading. Kids formed teams and read selected books that were high quality and age-appropriate. Then they competed against other teams at their school and other schools, answering questions about the books: characters, plot, symbolism, etc. The team and competition aspect motivated my boys to read, and they had a fun time doing it. I also read a couple of the books aloud to them. Because the books were chosen by a committee of professionals, I enjoyed reading them and discussing the important ideas they covered (immigration, bullying, discrimination) with my sons.