Having started a couple myself, I'd say a few of these are industry-specific. The main thing I learned (and learned to accept) is that at the beginning, nobody

Having started a couple myself, I'd say a few of these are industry-specific. The main thing I learned (and learned to accept) is that at the beginning, nobody cares. Potential customers don't care until you very clearly articulate something that matters to them. Friends and family care about YOU, but unless they're the target user, they also don't care about the business itself. Particularly for high achievers who are used to positive feedback, this lack of engagement can be pretty difficult. It would almost be easier if you had someone out there loudly rooting against you; at least then you'd exist to the world. Anyway, once I accepted that as a natural part of the process, the ups and downs got a lot easier.