Make progress that survives your mood.

If your work only happens when you feel like working, your output is really a report on your moods. Feelings are not the enemy here, they are simply an unreliable foundation, arriving and departing for reasons that have nothing to do with what matters to you. Progress that survives a bad mood is the only kind that accumulates, because bad moods are frequent and lasting things are built slowly.

Set a version of your work small enough to do on a low day. Ten minutes, one paragraph, one set. Do that version on the bad days rather than nothing, and keep the streak rather than the intensity.