Everyone learns a lot as a founder and going from an idea to an established company so would love to get a collection of the #1 lessons that each of you learned.
But also why you think that particular learning was the most important.
Rejection can be rewarding if taken positively
My friend and I started working on a silly project last year. It seemed like a good idea when we started, but the fact that we got started led us to approaching a potential user who rejected our idea and suggested other features instead. These needed skills where far fetched since none of us possessed them neither did we have money to hire a new developer. We decided to continue researching and utilised online resources to enhance the project. In the process, we have acquired an immense number of skills and ideas we have since added to the project.
We now have a refined business model due to the simple rejection.