I am very grateful for this post. One of the most common pieces of valuable feedback I got before starting my company (as a sole founder) is that I need to keep going no matter what - especially in times of self-doubt. I always considered myself to be confident, and self-assured (not obnoxious, just confident)...but starting a company is a completely different cup of tea. I have both a Computer Science degree + an MB…
If you are lucky, the self-doubt makes way for self-confidence eventually. Even for completely new things you start thinking, "well, I managed the last few times, it will probably work out OK this time too". I wonder if all the confident people I see starting out just have naive bravado or are very good at hiding their self-doubt.