Did he define 'work' during the podcast? Since he also mentions reading CS books, perhaps he isn't defining work as literally typing at the computer, but instead always improving. Think of what people could do if they took part of the 3 hours of TV watched per day and instead read a book.

He's also a high level grappler (nerd worlds collide if I ever had a chance to roll with Carmack :) ), which is not an easy feat.