Sedulous

/ˈsɛdʒ.ə.ləs/ adjective hard

A sedulous worker applies steady, painstaking effort to a task over a long period without giving up.

Through sedulous practice every morning before dawn, she eventually mastered the entire violin repertoire.

Memory Trick

Sedulous sounds like 'settle-us' - someone sedulous settles in for the long haul, refusing to quit until the work is done.