It's not that I can't write neatly, it's just that normally I'm writing too fast to care about how it looks (until later when I can't read my notes).
I was sat making notes on lecture slides today and I decided to practice writing neatly and to keep it up throughout the whole of the notes. It felt weird as I could feel the movements in my shoulder rather than my wrist but I managed to write neatly.
|My normal writing|
|A page of neat notes|
|My neater writing|