Each time I want to start a business, I feel excited in the beginning but when I think about sales, I feel overwhelmed and I bail out I'm a software engineer with full time job, I identify a business opportunity, I do all the planning, I create business model canvas / plan in few days, I do all the planning following lean approach , set a schedule etc. I know my ideal customer and market, briefly all the theory is done, but when it comes to taking actions, talking to people and get some clients on the phone, I feel overwhelmed, and afraid to get out of my comfort zone I end up dropping the ball quickly and the idea falls in the cracks.
Just do it. You're over thinking which is killing you. Just start and build as you go. When I started I had NO clue how to do anything but fix computers. I didn't know how to network or gain more customers. I just went out there and network my tail off and learned as I went. Talking to random people at an event was not in my comfort zone. Now, I kill it every time I go.
Bottom line, just start. Fear is fake. If it's not going to kill you then it's all made up in your head.