I feel almost like you. I am 38, I am a technical guy although I am more of a "jack of all trades" rather than very strong in one particular domain. I just started a new exciting job as a CTO for a young startup. I hope this will be my last job before going on my own. I started businesses a dozen years ago, and a side business more recently, but I am convinced that now I know much more about launching a new company and I feel I want to do it within a few years. And yet, I fear that a few years will go by, and then I will either try and fail, or just even give up on the idea.