Action Breeds Confidence
You already know not every idea you have is going to work out the way you planned. It's great to have a sound business plan, but if you're wringing your hands over all the little things that can go wrong, you're wasting valuable time. In the words of Dale Carnegie:
"Inaction breeds doubt and fear. Action breeds confidence and courage. If you want to conquer fear, do not sit home and think about it. Go out and get busy."