u/PuzzleBox64

You annoyed an old witch by refusing to lend her your front teeth for a potion.

That might sound bad at first, but you quickly realize that put in other words, the witches poorly worded curse seriously messed up and accidentally made it so that every day from now on will be better than the last. Your life satisfaction and your physical and mental well-being and abilities are now set at a floor and can't go any lower than today, your skills can't decay with time like most people's, and even a tiny fluke in the arrangement of molecules in your body that is beneficial to you will carry over to the next day, instead of dissolving away, granting you the ability to progress far beyond a normal human if you were to actually train yourself.