The main characteristic I've observed with all successful entrepreneurs is they all have a "definiteness of purpose," and a strong "reason why" they are doing what they're doing.
When you start anything worthwhile, you are going to run into obstacles. The obstacles could be things, situations, or people. That's when a lot of people decide it's too hard, or not worth it, and they give up.
But with a definiteness of purpose, and a strong reason why, obstacles are no longer barriers. Instead they become merely inconveniences or challenges that I need to moved beyond, so I can continue moving forward.