Like the author, I am usually good for two periods of about 90 minutes a day of extreme thinking work. I feel fine about this because in a sense I am always working, even if I just have a few peak periods a day. When I have a job, just about 100% of my intellectual life is thinking about the tech that can help my employer. If I want to read a tech article after dinner, it is just about always about something that might help the business.

I maintain work/life balance by taking a year off work between jobs. In these down time periods I both research a broad spectrum of things that interest me, and that is when I write my books.