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- David Goggins on the 40% rule, startups in 13 sentences by Paul Graham, and the dorm room where Facebook was built
David Goggins on the 40% rule, startups in 13 sentences by Paul Graham, and the dorm room where Facebook was built
The Z Fellows Newsletter - June 2, 2025
Welcome back to the Z Fellows newsletter! Every Monday we share 3 ideas - to help you build companies, ship products, and create your life's work.

1: David Goggins on the 40% rule
“When you think that you are done, you're only 40% in to what your body's capable of doing. That's just the limits that we put on ourselves.
Most people never push past discomfort—they listen to that first voice that says “stop.” The 40% Rule flips that voice on its head. When you think you're out of strength, you're usually not even halfway done. Pain isn’t the end—it's the beginning of a second wind.
Your limits are mostly lies. Your brain is trying to protect you from effort, not failure. The moment you want to quit is the perfect time to keep going. That’s when the real growth kicks in.“
Source: Can’t Hurt Me by David Goggins

2: Startups in 13 sentences by Paul Graham
Pick good cofounders.
Launch fast.
Let your ideas evolve.
Understand your users.
Better to make a few users love you than a lot ambivalent.
Offer surprisingly good customer service.
You make what you measure.
Spend little.
Get ramen profitable.
Avoid distractions.
Don’t get demoralized.
Don’t give up.
Deals fall through.

3: The dorm room where Facebook was built


Best of The Week
“In the end, a startup is a team of people working together to solve a problem. The product is just a byproduct.”
— Ben Horowitz, cofounder of a16z
— Z Fellows (@zfellows)
11:33 PM • May 31, 2025
“Pride is the enemy of learning” - @naval
— Z Fellows (@zfellows)
4:30 PM • May 31, 2025
Chad Byers (@chadbyers) on his billion dollar fumble:
— YESTERDAY (@yesterdaymgmt)
11:39 PM • May 27, 2025
See you next Monday,
- The Z Fellows Team
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