I wonder if it's always a zero day. I think that things and ways of thinking create momentum. The more you netflix and chill, the likelier you are to netflix and chill.

Yeah I definitely struggle with this. You need downtime to relax but it's easy to "over relax" just like it's easy to oversleep or overeat or overdo any other number of things that are healthy and necessary but only at the right amplitude and frequency. I think that's why it can feel so good to be in a rhythm. You get a nice oscillation going that rides the wave of momentum instead of some monotonic rise or fall that is going to lead to burnout or stagnation.