The ONE Thing by Gary Keller

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I used to think productivity meant juggling as many tasks as possible — crossing things off a to-do list just to feel like I was making progress. But deep down, I knew something was off. I was busy, not effective. Then I read The ONE Thing by Gary Keller, and it flipped everything I believed about focus and success.

The book asks one powerful question:
“What’s the ONE Thing I can do such that by doing it everything else will be easier or unnecessary?”

That question doesn’t just help you choose what to do — it helps you eliminate what doesn’t matter. It’s not about hustle or hustle culture. It’s about alignment. And the moment you start applying it, you feel it — that click of clarity, that forward momentum. That’s flow.

This post breaks down the most impactful lessons from the book and how I’ve paired them with tools like Motion (for smart time blocking) and Focus Blocks (for accountability that actually works). If you’ve been spinning your wheels, trying to do it all — this is your sign to stop. Start with one thing.

What Is The ONE Thing?

At its core, The ONE Thing is about extreme prioritization. It’s the discipline of asking yourself, again and again: What’s the one thing that matters most right now?

Keller calls it The Focusing Question — and it’s deceptively simple:

“What’s the ONE Thing I can do such that by doing it everything else will be easier or unnecessary?”

This question slices through overwhelm. It replaces guesswork with purpose. Whether you’re staring down a cluttered to-do list or trying to decide which goal deserves your energy, this question points you toward what truly moves the needle.

The brilliance of the book isn’t just the question — it’s the mindset shift. Most people try to do more. The ONE Thing teaches you to do less — more deliberately. That’s not laziness. It’s leverage. It’s choosing your next action with precision instead of pressure.

And once you apply it, the ripple effects show up everywhere — in work, health, relationships, even parenting. You stop reacting. You start leading your time, instead of letting it lead you.

Focus Blocks – Because I am a member, I can hook you up with FREE 1 month.
The best way for you to get started is:

1. Watch the masterclass at:  https://focusblocks.io 
2. Once you have watched the training, just email support@focusblocks.io and tell them that Casey – kayhsee@gmail.com sent you so that they will give you a FREE 1 month.

The Domino Effect: How Success Builds

One domino can knock over another domino that’s 50% bigger. Stack enough, and you get exponential impact from what looks like a small start. That’s not a metaphor Gary Keller throws around lightly — it’s the foundation of how success builds over time.

In The ONE Thing, Keller explains how success isn’t a straight line — it’s a geometric progression. You don’t achieve your big goals all at once. You line them up like dominos, starting with the smallest, most manageable one. Then you knock it over.

That first win builds momentum. The next one gets easier. Then the next. And eventually, you’re knocking over goals that once felt impossible — not because you worked harder, but because you worked smarter, in sequence.

“Success is built sequentially. It’s one thing at a time.”

This is the opposite of scattershot effort. It’s not about doing everything. It’s about doing the right thing — and letting that action trigger a chain reaction.

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The Lie of Multitasking

We love the idea of multitasking — checking emails during meetings, listening to podcasts while replying to texts, juggling tasks to “save time.” But as The ONE Thing makes clear, multitasking isn’t efficient — it’s a myth that’s quietly wrecking your focus.

Gary Keller breaks it down: your brain can’t focus on two things at once. What you’re really doing is task-switching — rapidly shifting attention from one thing to another. And each time you switch, you lose mental energy and momentum. Studies back this up: productivity drops by up to 40% when multitasking becomes the norm.

“Multitasking is merely the opportunity to screw up more than one thing at a time.”

Deep work requires undivided attention. Whether you’re writing, strategizing, designing, or learning, the quality of your output depends on how long you can stay focused on one thing without interruption.

This isn’t just about productivity — it’s about sanity. When you stop trying to keep all the plates spinning at once, you feel more grounded. You do better work. You feel less overwhelmed. And ironically, you often get more done.

Time Blocking: Make Space for What Matters

Knowing your One Thing is powerful. But it won’t matter unless you protect time to do it. That’s where time blocking comes in — one of the most practical strategies in The ONE Thing.

Time blocking means reserving chunks of your calendar for your highest-priority work — and treating that time like a meeting with your future self. You don’t cancel. You don’t multitask. You show up and do the work.

“If it’s not on your calendar, it doesn’t exist.”

Keller recommends blocking out your One Thing first thing in the day, before distractions creep in. Even 1–2 hours of focused, uninterrupted effort can radically move the needle. It’s not about quantity of time — it’s about quality of attention.

Personally, I’ve found the app Motion game-changing for this. It automatically builds your day around your priorities, rearranging lower tasks and protecting focus time. If traditional calendars haven’t worked for you, Motion makes time blocking frictionless — especially with its 7-day free trial.

The real magic? When you consistently time block your One Thing, you don’t have to hustle harder. You just build the habit of doing what matters first.

Goal Setting to the Now

Big goals are inspiring — but they’re also intimidating. That’s why so many people stay stuck at the “someday” stage. The ONE Thing offers a clear framework to break that paralysis: Goal Setting to the Now.

It starts with your long-term vision — the big goal that feels years away. Then you work backward:

• Someday Goal → What’s the ONE Thing I want to achieve long-term?
• Five-Year Goal → Based on that, where do I need to be in five years?
• One-Year Goal → What must happen this year to stay on track?
• Monthly Goal → What’s one milestone I can hit this month?
• Weekly Goal → What should I focus on this week?
• Daily Action → What’s the ONE Thing I need to do today?

It’s like reverse-engineering your success. Instead of waking up and reacting to your inbox, you wake up already knowing what deserves your attention.

“Your next step is always connected to your ultimate goal.”

I’ve found this approach eliminates decision fatigue. You stop wasting energy trying to figure out what’s important. You know what’s important — because it’s tied to the future you’re building.

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Why Purpose Is Your True Priority Filter

Without a clear purpose, everything can feel urgent. But when you know why you’re doing something, decisions get easier. You stop chasing every shiny opportunity and start filtering actions through what really matters.

In The ONE Thing, Keller and Papasan emphasize that purpose isn’t fluffy. It’s practical. It’s the foundation for setting priorities and the fuel behind your ability to stay consistent. When you’re anchored in purpose, you’re less likely to get distracted or burnt out — because your actions are aligned with something deeper.

“Purpose gives you clarity. Clarity gives you power.”

This echoes ideas from frameworks like Ikigai — the Japanese concept of finding fulfillment at the intersection of what you love, what you’re good at, what the world needs, and what pays. When your One Thing overlaps with your purpose, work becomes more than productivity — it becomes meaningful.

Personally, whenever I’ve lost momentum, it’s usually because I was chasing someone else’s goals. Getting quiet and reconnecting to my why has always been the reset I needed.

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The Six Lies That Sabotage Success

Part of what makes The ONE Thing so powerful is how it debunks the common myths we take for granted — the habits that feel productive but secretly hold us back. Keller calls these The Six Lies, and they’re worth unpacking:

1. Everything matters equally – It doesn’t. Most things are distractions. A few things move everything forward.
2. Multitasking – Already covered, but it bears repeating: split attention means weaker results.
3. A disciplined life – You don’t need to be disciplined all the time. Just long enough to build habits around your One Thing.
4. Willpower is always on will-call – Willpower fluctuates. You have the most in the morning. Use it wisely.
5. A balanced life – Balance is a myth. Extraordinary results require intentional imbalance — leaning hard into what matters.
6. Big is bad – Thinking small feels safe, but it limits your potential. Big goals create big energy and clarity.

“Success is about doing the right thing, not doing everything right.”

Each of these lies creates noise — and clarity comes from calling them out. When you let go of what doesn’t serve you, your One Thing becomes obvious.

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Habit Formation and the 66-Day Rule

You’ve probably heard the old myth: it takes 21 days to form a habit. Not true — and The ONE Thing sets the record straight. According to research cited in the book, it actually takes an average of 66 days to build a habit that sticks.

That means if you struggle with consistency, it’s not because you’re failing — it’s because the process takes longer than we’ve been led to believe. Some habits take even more than 66 days, depending on complexity. The good news? Once you push past the resistance, the behavior becomes automatic — and that’s when real momentum begins.

“Success is about doing the right thing long enough for it to become a habit.”

Keller encourages readers to focus on one habit at a time — and track their progress daily. That’s where the 66 Day Challenge Calendar comes in. It’s a visual accountability tool that helps you stay the course and celebrate daily wins.

Personally, I’ve found the act of physically checking a box each day incredibly motivating. It’s not about perfection — it’s about showing up again and again until it feels natural.

👉 Ready to lock in your One Thing as a habit? Download the 66 Day Challenge Calendar and start tracking today. Post it somewhere visible. Make the commitment real. Momentum builds one box at a time.

Tools to Help You Find and Stick to Your One Thing

Knowing your One Thing is only half the battle — the real transformation comes when you protect it, act on it, and stay consistent. That’s where the right tools can help bridge the gap between intention and execution.

🧠 1. Motion: Smarter Time Blocking

Motion takes the guesswork out of scheduling. Instead of manually planning your day, it dynamically blocks time for your top priorities — adapting in real time if something changes. I use it to ensure my One Thing always gets dedicated space, even when life throws curveballs.
👉 Try Motion’s 7-day free trial and experience what it’s like to protect your most important work automatically.

🔒 2. Focus Blocks: Real-Time Accountability

Focus Blocks gives you live, distraction-free work sessions with others who are also focused on their One Thing. Think of it as coworking meets commitment device. You show up, declare your focus, and get it done.
Because I’m a member, I can share a free 1-month trial:

• Watch the intro masterclass at focusblocks.io
• Then email support@focusblocks.io and tell them Casey (kayhsee@gmail.com) sent you

🧘‍♀️ Optional Add-Ons

If you want to take things further, tools like the Muse headband (for tracking meditation focus) or platforms like The Flow Genome Project can help you build the mental clarity needed to stay on task and tap into flow more consistently.

The right tool doesn’t replace discipline — it reinforces it. Pick the one that removes the most friction for you.

Less Really Is More

We’re taught to do more. Chase more. Be more. But The ONE Thing flips that idea — and it works, not because it simplifies your goals, but because it simplifies your path.

When you focus on less, you make space for better. Better results. Better alignment. Better energy. You stop scattering your effort and start building momentum — one intentional choice at a time.

For me, integrating this philosophy changed the way I work, parent, and plan. I stopped trying to balance everything perfectly and started prioritizing purposefully. It’s not always easy, but it’s clearer. And clarity is power.

“Extraordinary results are directly determined by how narrow you can make your focus.”

If you’re feeling overwhelmed or stuck in motion without progress, here’s your permission to pause — and ask the question that started it all:

“What’s the ONE Thing I can do, such that by doing it, everything else will be easier or unnecessary?”

Ask it daily. Let it guide your calendar. Let it shape your goals.

And if you need support?

• Use Motion to protect your focus
• Try Focus Blocks for built-in accountability
• Download the 66 Day Challenge Calendar to track your habit

Start small. Start now. Start with your One Thing.

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