Repeat it until it’s boring, then do it a few more times. Boring is where it becomes yours.

Competence and automaticity are separate stages, and most people stop at the first. You can do it correctly with concentration, which feels like arrival, but under pressure or fatigue it falls apart because it still needs your attention. Repeating past the point of boredom moves it somewhere else, where it runs unsupervised and leaves your attention free for the harder parts.

The point where it starts feeling easy is the signal to keep going rather than to move on. Do a few more than you want to. Boredom in practice usually means the skill is nearly yours.