Some days are for acceleration; others are simply for keeping the wheels turning.

Not every day can push things forward, and expecting that is how people end up abandoning practices entirely. Some days the honest goal is simply that the thing does not stop, that the minimum happens and the thread stays intact. Those days look like nothing and are the reason the good days have something to build on.

Define your minimum in advance, small enough to do while tired or unwell. On a bad day, do that and count it as a success rather than a failure. The wheels turning is a genuine achievement on the days when turning them is all there is.