Anyone can practice on a good day. The bad days are where the gap between you and everyone else gets built.

Good days require no decision, so they do not separate anyone from anyone. The gap gets built on the days when you feel flat, sore, uninspired or slightly resentful, because most people reasonably stop there. Doing a reduced version on those days is worth more than a heroic session when everything already felt easy.

Set a floor rather than a target, the smallest amount that still counts. On the bad days do exactly the floor, with no guilt about the size of it.