David Epstein’s new book Inside the Box came out this week. And it’s one of the most interesting books on creativity I’ve read in years. (You may know his first book, Range, which I also loved.)

The counterintuitive premise: constraints make us better. 

The idea I keep coming back to is “universal design”: build for the most-constrained user, and the result is better for everyone.

SUPERHUMAN SCORING

In every edition of System Sunday, I assess the featured system across three superhuman dimensions: impact, setup, and maintenance.

Unlike your typical review, I focus on factors that influence personal growth. Get to know the evaluation system.

Impact (10.0/10)

In the late 1980s, Sam Farber watched his wife, Betsey, struggle to peel apples. She had arthritis, and the thin metal handles on standard peelers dug into her hands. So Farber built her a peeler with a fat, soft, rubber grip designed for hands that hurt.

Then something funny happened. Everyone preferred it. Professional chefs and kids learning to cook. People with no hand problems at all. The OXO Good Grips peeler became a kitchen staple, and the company built an entire product line on the same principle.

The pattern shows up everywhere once you see it. When cities started sloping the corners of sidewalks in the 1970s, it was a fix for wheelchair users. Then everyone started using them. Parents with strollers, delivery workers with dollies, travelers with rollerbags, anyone who has ever pushed a shopping cart. A design built for the most-constrained user serves everyone, because everyone is constrained sometimes.

What David does in the book is show that this isn’t a feel-good story about accommodation. It’s how good design actually works.

The constrained user, in your own life, is you on your worst day.

Tired and overcommitted. The version with twenty minutes to finish a task instead of an hour, running on five hours of sleep.

Most of us design routines for an idealized version of ourselves who is rested and fully in control. That person barely exists.

The peeler that works for arthritic hands works for every hand. The routine that survives your worst day works for every day.

The chapter focuses on product and policy design. But the concept scales surprisingly well. The same logic that builds a better peeler can build a routine that survives a hard week.

Setup (8.5/10)

The all-or-nothing trap kills most routines.

You can’t do the ninety-minute morning, so you do nothing. You miss Monday’s workout, so the week feels shot. One bad day becomes a zero day. Zero days compound into broken streaks you eventually stop trying to rebuild.

The fix is to give every system a floor: a non-negotiable minimum that still counts as a win, even on your worst day.

1. Name your edge user

Picture the most-constrained version of yourself you’ll have to operate as in the next month. The work trip or the deadline crunch.

That version is your edge user.

Mine is the version of me in a hotel room running on five hours of sleep, with no kitchen and no gym. If a routine doesn’t survive him, it doesn’t really exist.

2. Define the floor, not the ceiling

Most of us design routines around the ideal day: ninety minutes, full gym, perfect headspace. That’s the ceiling.

The floor is the smallest version that still counts as a win.

For my morning routine, the floor is drinking water, getting sun, and writing my top priority down. For my workout, twenty pushups and a 10-minute walk. For reading, five pages.

None of these are impressive. That’s the point. They’re easy enough that the hotel-room version of me can still hit them, which means almost no zero days.

3. Build in flex above the floor

Once the floor is defined, you can stack on top of it without the whole thing becoming fragile. The floor always runs. Everything above it is a bonus.

• The floor workout is twenty pushups and a 10-minute walk. The full version is 45 minutes at the gym.
• The floor morning is water, sun, and my top priority written down. The full version adds journaling and meditation.
• The floor reading is five pages. The full version is an hour before bed.

Either way, the streak holds.

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Maintenance (9.5/10)

One question per month: Which of my systems doesn’t have a real floor yet?

Maybe it’s a diet that breaks the moment life gets social. Or a writing practice that disappears during travel.

Identify the fragile system. Shrink it until it survives the worst day.

Over time, the variance between your good and bad days narrows. The impressive thing about people who seem to have it together is rarely that their best days are extraordinary. Their worst days are simply remarkably hard to spot.

BRINGING IT HOME

Inside the Box is the kind of book that reframes how I think about pursuing creative breakthroughs and designing my routines.

The universal design idea is just one of many. The book also has sharp insights on commitment devices, breaking through bottlenecks, satisficing, and more. Easily one of my favorite reads in 2026. I highly recommend it.

You don’t need a heroic version of yourself. You need a system that holds up when the heroic version is unavailable.

Build the system for the worst day. Watch how light the good ones feel.

All systems go,