My moment of maximum fear was early on when I was still a sole trader. I took on too much, was ill and couldn't deliver the work. The client was very understanding and forgiving but it taught me a lot about business.
My moment of maximum satisfaction was when I realised I really could do this and run my own company. Encorporating the business and growing it into Blink Design Studios was a turning point in my life and I haven't looked back.