I had experienced burnout about a year before that. My productivity dropped: I used to submit about five changes a week to the codebase, and that dropped to once a week on average, on the same project and in the same environment. The graph looked as if it had fallen off a cliff.
That was a mistake. Search is the biggest and most complex product at Google, and semantic search (the thing that gives you a direct answer to a query instead of links) is one of the brainiest teams around.
At that point, my relationship with the manager and director started to deteriorate too. They got a new guy on the team but couldn't get much work out of me.
My manager's first instinct was to enforce some discipline. He made me sit in front of the computer, essentially, and he monitored when I came and went, which made things even worse.
In private discussions, I was asked why I wouldn't just resign. I said I was happy with my Google salary. (It was around $180,000 a year at the time.) I figured that if Google wasn't happy with my performance, it could feel free to fire me, but I wasn't going to jump myself.