"I tried prioritizing my work, focusing on the things I felt the most passionately about, but when I tried to work on the projects at the top of this list I couldn't summon any energy. Yet I spent hours and hours thinking obsessively about the ultimate point of my work."
I mean, heck, the guy said he was reading 50 (no doubt challenging) books a year on his work. That's insane.
It's pretty simple: you can't work at an insane pace forever, and eventually your subconscious will rebel and stop working with you.
In my case, it felt like my intentions and actions were connected by a plastic gear, and I had spent so many years jamming that gear as hard as I could that it stripped the teeth off of it. My intentions could spin as hard as they wanted to, but eventually I just found it impossible to do anything.