Do you find it hard to start something new with no sure end result?

Have you started a new business and have dreams of it being successful but can't 100% say it will be? What was the hardest part of the process? For me it was saying YES and jumping into it head first. I found it to work in my favor to be naive of how much work it was actually going to take but I am glad I took the first leap. Let me know your thoughts!!