It’s not so much that horrendous self-doubt is necessary for great writing, but rather that spending lots of time practicing the craft tends to produce both.
That’s my life at the moment: when I need a break from work, I do other work.
It’s good advice to keep track of how you spend your writing time.
It’s better advice to have no record whatsoever of how you spend your writing time.
Crying is an important step, too.