Sometimes you question your own motives. You wonder why you chose the path you did. Are you smart enough? Can you handle the pressure when it arises? Are you just doing it for the money?
We all have doubts and we all have question. You want the questions, because your mind will begin formulating answers to those questions. How else are you to know if what you picked is right for you? The best way to figure out something is to fail at it. If you can fail at something, and learn from it in order to get through it on your next attempt, you might have something.
Just get used to experiementing if you have not found that special thing. If you have found out what makes your heart metaphrically skip a beat, keep at it, and focus on the love of the craft.