” Concentration is so hard to achieve, and even harder to maintain for hours. The key for me is to solve one set of problems at a time. I try to maintain a constructive level of dissatisfaction, and to hang in there until I really feel it can’t be improved.”
Note his words “constructive level”. None of that sweeping “it’s all rubbish” defeatist thinking.
Flavour what you’re doing with both spice and sugar, pessimism and optimism, not-yet-achieved and achieved.