Bartlett borrows and expands an idea he encountered in his research: the most important mindset shift for any founder or ambitious professional is from 'How?' to 'Who?' When you face a problem, the instinct is to ask: how do I solve this? How do I learn to do this? How do I figure this out? This question turns you into the bottleneck. Everything depends on your ability to acquire the skill and apply it, which takes time and often produces mediocre results in areas where you are not naturally talented. The alternative question is: who already knows how to do this? Who has spent ten years mastering this specific skill? Who could do in an hour what would take me six months to learn and still not do as well? This is not about outsourcing everything. There are skills worth developing deeply. But the 'who' question forces a discipline: before investing significant time in learning something yourself, ask whether recruiting the right person or partner would produce a better result faster. Bartlett applies this at every level, from hiring to partnerships to mentors to advisors. The highest-leverage version of the question is not about outsourcing tasks but about surrounding yourself with people who are better than you in the areas that matter most to your goals.