Here's what I've noticed, not only in myself, but in others:

1.) Not knowing their strengths and weaknesses and how they relate to their business. Play to your strengths. In the areas where you are weak, delegate or outsource.

2.) Don't give up. Perseverance will be your greatest asset.

3.) Have a clear mind. Learn how to meditate. 5-10 minutes of silence will do wonders.

4.) Learn to adapt and be flexible.

5.) Validate the business before going all in. Like another person who answered earlier, don't "play business" and get a website, business cards, etc. Bootstrap the business for as long as possible to find out if it is something people want and if it will be profitable.

Everyday is challenge, but you can't win if you don't get in the game.