Startups are wonderful, freeing experiences. You can build exactly the company and culture you want, balancing so many of the things that you didn't have control over at a bigger company.

Then you get customers.

Customers don't care if you're burnt out.

Customers don't care if you're transparent and fair to your colleagues.

You get grace periods when you're first starting out, or first signed a couple contracts, or after delivering a few key efforts.

But at the end of the day, customers are where the pressure comes from, because they are the sustaining force of your business.