What Doesn't Seem Like Work?
This excerpt -"what he really liked was solving problems. The text of each chapter was just some advice about solving them. He said that as soon as he got a new textbook he'd immediately work out all the problems—to the slight annoyance of his teacher, since the class was supposed to work through the book gradually."is literally me. I did that. Every year at my school I did exactly that. Once I actually turned in my solutions and my math teacher was quite upset because she didn't know what I'd do for the rest of the year in her class. She thought I was being arrogant and I should take in the material slowly, not swallow it all like a whale. But I wasn't arrogant or anything, because unfortunately this skill didn't transfer to the rest of my classes. I wasn't particularly good at history or physics or anything else, only math. Even now, I have tons of Schaums at my home. Like this one - http://www.amazon.com/Schaums-000-Solved-Problems-Calculus/d... 
I work problems in it just because it is a craving - I simply have to solve it. Sadly, society doesn't pay for this sort of addiction. I have been a professional programmer for the past 2 decades to pay the bills, but I secretly hate programming, debugging, programmers, git, the whole enterprise - just seems so stupid & futile. But hey, atleast I can spend my salary on Schaums.