I have found that I am so much happier when I'm able to accomplish so much before the middle of the day. Mornings, I've now found, bring me joy, if not in the moment than surely a few hours after I've woken up at least.
The truth is, it's not easy to write a novel. Like a clock, a novel has many moving parts that all need to work together in perfect balance. Pace. Momentum. Tension. Plot. Characterization. Story arc. Character arcs.