A few years ago I had to work long hours, and I do not have time to read. This situation really annoyed me. So I started to look for new ways to gain knowledge. After a few months, I read an article which explained audio books. I was thrilled by the article. If I listened to audio books, I could change my commuting time into learning time, so I started buying some audio books.
At that time (2005) Japanese language audio books were quite rare and very expensive( more than \5000 for a 60 minute book). However English language audio books were less expensive, and there was a much bigger range. I realized that if I could understand English, I could access many of these works.
Even now there is not much change from the situation in 2005. Some companies produce Japanese language audio books, but there are relatively few Japanese audio books, as they are too new to be accepted by many Japanese people.
When I graduated from university I did not have to study English, because I did not use English at work. I stopped studying English. But I resumed studying English because I wanted to listen to many audio books. Audio books were the biggest reason why I started studying English again.