It’s time to get psyched.

The Tasks in 100 Days, 100 Grand are simple actions in logical sequence, most involving spreadsheets, documents, and websites. But even if you’re expert with Excel and Word, you’ll find your brain turning backflips at times—and wonder why.

The reason involves something called System 1 and System 2. The terms (shortened to S1 and S2) were coined by psychologist Daniel Kahneman to denote the main ways humans respond to information. Each can be summed up in a paragraph, and they’re the only bits of proper psychology in the book. (After all, psychology is a complex subject, and an instructional text on freelancing isn’t the forum for explaining it even if I had the training.) But a basic outline of the idea gives you a useful model for understanding customer motivations. Call System 1 the feeling system and System 2 the thinking system.

System 1 is what governs most people’s behaviour, most of the time. It’s your animal instincts and emotional responses, evolved over millions of years, most spent trolling the African grasslands in fear and hunger. That sudden rush of adrenalin urging you towards fight or flight, that rush of anger when you see someone threatened, that irrational fear of boarding the plane because you saw a crash on the news yesterday—all these reactions are from your System 1.

S1 thrives today because for most creatures, reacting without thinking is a useful skill. (You don’t want to think for too long when your food chain’s apex predator is looking at you as if you’re labelled LUNCH.) System 1 attaches great importance to what’s here and now, right in front of your nose. It’s subjective, driving you to do what feels right at the time.

If System 1 shows your animal side, System 2 is arguably what makes you human. It’s your ability to think critically and reason logically. It’s how a bunch of bipeds in Africa started wearing clothes, making tools, and building communities. System 2 lets you plan ahead, assessing information with a cool head and making decisions that deliver expected outcomes.

System 2 is harder to use than System 1. Because it asks you to stop and understand stuff, grasp concepts and engage in abstract thought. That’s why you’ll find parts of 100 Days, 100 Grand hard work, even if you find the individual Tasks simple. Every chapter makes you think and reach decisions using S2, not S1. System 2 is objective, forcing you to analyse situations and make considered responses.

(System 2 is the reason 100 Days uses a lot of checklists. Checklists force you to put your thinking head on, and make decisions rationally and logically.)

If there’s one difference between 100 Days and a self-help book, it’s that 100 Days forces you to use your System 2, not the feel-good of your System 1. Although eliciting reactions from other people’s System 1 is one of the bigger tasks you’ll check off along the way. Because there’s another term for “eliciting reactions from System 1”. It’s known as Marketing.