How to Build a Successful to-Do List App

I'm really curious about how the early days went too like how did you get to the point where this to-do list app that no one had really ever heard of became such a massive company and in such a popular application today. So give me an example of some of these things that you've changed or maybe a point at which things were too painful to keep doing it the same way you were doing it before. Yeah and it's challenging because you have to do all of the stuff to run your company and make sure that everybody is effective and communicating well and successful but at the same time you actually want like your product to be good right? I would probably never have started to do it