Finding a co-founder, plus making those first few hires, is easily the most challenging part. You're going to realize you can't solve every problem, and you'll need help. Finding your team is like finding a life partner- a great one that complements your strengths and weaknesses could set you up for life. The wrong one will result in mismatched effort, finger-pointing, and time spent away from the customer. It's one thing to ask a user to give you $20/mo. It's another thing to ask another human to wake up with you every day and spend their prime working on your vision in opportunity cost of working on something else. It's going to be the most important sell of your life!