Books are an excellent way to gain a lot of knowledge on a huge variety of topics, and are also a great exercise for your brain. Its not that difficult to go through 20 or more books in a year you only need to make it a habit, discover your type of books and find a bit of time for reading here and there. One way to do that is to dedicate 10-15 minutes every day to reading. The best time to do so is right before you go to sleep. If you do that (and are reading an interesting book) you will end up reading for much longer and much more often!