Mastery is mostly the stretch where practice stops being fun and you keep booking it anyway.

Early progress supplies its own motivation because improvement is fast and visible. The middle does not. It is a long corridor where the gains are small, the novelty is gone, and continuing is a decision rather than an impulse. Almost everyone who got good went through that corridor with no particular enthusiasm, simply because they had decided it was not optional.

Expect the flat stretch instead of reading it as a sign you chose wrong. Set the schedule while you are still interested so it survives the part where you are not. Count the reluctant days the same as the rest.