Long story.
When I was about nine or so I read Colour of Magic, loved it, and forgot it. That mom got me a copy of Eric from the library narrated by Tony Robinson, and I loved it, and forgot about it too.
Then a few years later mom got me the movie Hogfather around Christmas time. I watched that, loved it, listened to the audio book, and was looking for another Pratchett audiobook when I found Jingo.
Eureka!
I couldn't get enough of Sam Vimes! I went on to read the rest of the Watch books, starting from the first, and eventually transformed into the Disc fan I am today.