What better than reading something that implicitly justifies the fact that you're reading it?
Assigned problems are problems you’re told to work on. Numerous psychology experiments have found that when you try to “incentivize” people to do something, they’re less likely to do it and do a worse job. External incentives, like rewards and punishments, kills what psychologists call your “intrinsic motivation” — your natural interest in the problem. (This is one of the most thoroughly replicated findings of social psychology — over 70 studies have found that rewards undermine interest in the task.)5 People’s heads seem to have a deep avoidance of being told what to do.6