Justin Sacks MD MBA FACS

Marcus Aurelius wrote this over 1800 years ago: “Think of yourself as dead. You have lived your life. Now take what's left and live it properly.”

I won't say it again

High performers are rare. In most rooms, they feel out of place. Too intense. Too hungry. Too much. But when you put them around others like them, they come alive. Not because they need competition. But because they finally feel understood. Ambition multiplies in the right environment.

Andrej Karpathy left an AI agent running for two days. It made 700 changes to his code. Found 20 improvements he'd missed over two decades of manual work. Cut his benchmark by 11%. The whole thing is 630 lines of Python code and runs on a single GPU. I spent a week digging into how it works and what it means. Wrote it all up here.

Working on something ambitious is like climbing a mountain that’s covered in fog. You can't see a clear path to the top. You have to take a few steps into the unknown to be able to see the next few steps in front of you. Inevitably, sometimes you’ll end up a local maximum and have to backtrack. That’s fine, just keep moving.

Just do things.

⚡️The agent hype is overstating autonomy and understating drift, hidden state, and accountability. Agents will absolutely matter. They will automate a lot. They will become very good at bounded workflows. They will save companies real money. They will replace a lot of repetitive labor. But the internet is jumping from: “agents can execute multi step tasks” to “agents can reliably run the world” That jump is bullshit. Here is the clean line. Agents work when: •the goal is clear •the environment is legible •feedback is fast •mistakes are reversible •the rules stay stable Agents fail when: •the objective is fuzzy •truth arrives late •the environment adapts •the costs of error are high •hidden incentives matter more than visible data That covers a huge amount of high signal work: forecasting strategy capital allocation negotiation leadership geopolitics hiring creative direction crisis management The deeper reason is simple. A lot of valuable work is not “doing steps.” It is deciding what the steps should be, which signals matter, when the frame changed, and when the whole process needs to be abandoned. Agents are much better at execution than at hierarchy of meaning. And the internet keeps confusing polished execution with reliable judgment. That confusion comes from demos. Demos reward visible competence. Real life punishes silent failure. So this is my actual view: Agents become powerful subordinates before they become trustworthy principals. They will expand the output of good operators. They will not eliminate the need for good operators in the highest leverage domains. The strongest model is still: human owns the loop agent runs the machinery That is the real boundary.

The most dangerous person in any room isn’t the smartest one. It’s the one who can’t stop thinking about the problem at 2am when everyone else is asleep. Talent sets a ceiling. Obsession blows through it. - Mozart wasn’t just gifted. He was a child who physically couldn’t stop composing. - Newton didn’t “discover” gravity in an afternoon. He spent 20 years unable to think about anything else. Society glorifies the gift because it’s comfortable. If success is talent, mediocrity is excusable. But obsession is a choice. And that makes most people deeply uncomfortable. The truly obsessed don’t grind. They can’t stop. That’s the part nobody talks about. Discipline is forcing yourself to work. Obsession is struggling to do anything else. You don’t manufacture it. You find the thing that already has its hooks in you — and stop apologizing for how deep they go. Your talent was assigned to you. Your obsession? That’s yours.

Jensen Huang on the smartest person he's ever met;

In my experience, "I don't have time" usually means "I haven't decided it matters." Time isn't found. It's created.

🚨: Scientists mapped 1 mm³ of a human brain ─ less than a grain of rice ─ and a microscopic cosmos appeared.

Joy is a competitive super power. Alysa Liu retired from figure skating at 16. She was tired of not not having fun, tired of being consumed by her sport. She came back two years later with a new goal: to have as much fun on the ice as possible. And now she’s an Olympic gold medalist. Liu won her first national title when she was just 13. But by 16, after competing in the 2022 Olympics, she decided she’d had enough and stepped away. She said pressure and losing her identity trying to be an elite athlete made it all miserable. But then, she said she went on a ski trip that reminded her just how much fun she could have doing a sport. Something in her brain clicked. Maybe she could bring fun to figure skating. Maybe she could approach it in a way that could be full of joy and life and love. She unretired at 18 and won a world championship the next year. At 20, she was ready to face these Olympic games differently than in 2022. Liu went into the women’s figure skating final in third place. After her short program, she said: “Even if I mess up and fall, that’s totally okay, too. I’m fine with any outcome, as long as I’m out there.” One of the greatest competitive advantages is having fun. People love to romanticize the athlete, artist, or entrepreneur who has a chip on their shoulder, fueled by anger and resentment. But the truth is that if you’re not having fun, you are not going to last long at whatever it is you do, and you certainly won’t get the best out of yourself. There’s a foolish idea that you either have to be full of intensity or full of joy. But that’s nonsense. It’s no surprise one of the first things out of Alysa’s mouth after her free skate was: “That was so much fun!” Joy and intensity can coexist, and in the best performers, they almost always do. Alysa is unapologetically authentic and true to her values. She has said where she used to skate to win and be technically perfect, she now uses competition as a chance to show her art, to have fun, and to put herself out there. She’s a fierce athlete with an infectious sense of joy in her sport. And she broke USA's 24-year gold medal draught in women’s figure skating doing it. Excellence requires focus, determination, a little bit of crazy, at times obsession, and living a mundane lifestyle that many people would find boring. But excellence also requires that you find deep joy in your craft, that you learn how to have fun while working hard. What makes for excellence—and not just in sports, but in anything—is the combination of intensity and joy. It’s the latter that makes the former sustainable.