The fun theory is the theory that if you make a normal task fun it will distract you enough to make you forget it's something you don't like to do. Such as walking up the stairs no one wants to do it because they have to carry stuff or too tired or lazy to do it. What if they change the stairs into a piano so when you walk up it's just music and you distract yourself from walking to paying attention to the noise you hear. You then get curious so you keep going and then before you know it you want to keep doing it because it isn't boring. You're not just walking up a flight of stairs you're making music while you do it. It's amusing to see because they go back down and start playing like if there kids once again and the kids are so excited to make the music while they go.
If i could redesign a unpleasant boring task into one that is more fun i would redesign taking boring plain notes. I would redesign it into making a drawing about each specific note to memorize easier. Such as if you are talking about cells in class what better to do then draw each part of it out if you remember what each looks like as a whole instead of trying to force your brain into remembering a whole class of notes about each one you would just have to remember how it looked and another picture of what it reminds you about.