Great article. I never heard the "zero-day" concept before but I have been practicing it for a while now. On days I feel low on energy, or when I have a lot on my plate I make it a point to at least do something. I tell myself "something is better than nothing" and the beauty of it is that you can create little mantras to keep you going. For example when I feel tired and don't want to put in a long or hard run I tell myself "short run is better than no run." : ) I play the same game with writing.