1/ What is “product/market fit”? I’m not sure I can give you a definition. But maybe I can share what the subjective difference is in how it feels when you have it and when you don’t. Founding a startup is deciding to take on the burden of Sisyphus: pushing a boulder up a hill.

If you stop pushing, the boulder doesn’t move. Every inch you push the boulder requires full effort. If you get distracted or stop working, the boulder might actually roll back down. You’re sweating and shoving and progress comes slowly and incrementally.

3/ But the trick is, you aren’t really Sisyphus. The gods have not condemned you. It might feel like you’re Sisyphus, you might have the boulder roll back down to the bottom again and again. You might try rolling the boulder up a neighboring hill and fail again.

4/ But there is this moment that comes, eventually, where you crest the top of the hill. And suddenly you’re pushing the boulder and it’s moving so easily! You’re pushing it on the summit, and the hill doesn’t fight you. It takes only a little effort to make progress.

5/ You have reached the promised land of product/market fit. And now the boulder is starting to roll down the hill, you actually don’t need to do any work to make progress. Customers are coming to you, you have more demand than you need. And the boulder starts to accelerate.

5/ and now your job is just keeping up with the boulder. You’re jogging, then running, then sprinting. Instead of strength, you need endurance. Instead of focusing on the next inch you have to win, you need to be looking hundreds or yards ahead where the boulder is rolling.

7/ pushing a boulder: don’t have product/market fit. Chasing a boulder: have product/market fit. Both are very demanding, but feel totally different. If you’re still pushing the boulder, you don’t have it yet.

8/ incidentally this is why co-founders are so essential for the first part of the startup journey. Even if one person is strong enough to push the boulder, having someone else to help and maybe keep it from slipping back helps immensely. Less so when you’re chasing downhill.

9/ apologies for my very poorly numbered tweets, and thank you for reading.