What has most surprised you about founding a startup?

The amount of "consultants" messaging me on linkedin.

How hard it would be to find constant motivation to keep moving, it is a marathon and a long play --- you have to dig deep to keep consistent in what you do. You can sell anything, if you work at it hard and long enough.

Building is the product is actually the easy part. It's building a community around your product with people who care for it is challenging.