I find I'm most challenged by things I really care about, because I really want to do them well. It causes quite a bit of anxiety. But that very thing you're afraid of is kind of like a blessing in disguise. If you didn't have that fear, you wouldn't have the other side - courage and bravery, positive emotions.As an actor, you get used to those fears, and you're almost happy when they show up. It makes you learn your lines and prepare.