Many people lack of self-assurance when facing situations which are new to them. They think that they can´t solve the problem or they are not able to manage the task given because they never had done something similar before.
But in many cases, it helps to say to yourself that this unknown problem is just an opportunity to get better in what you are doing. You can´t know everything but when you believe in yourself, you are not afraid of the change. With enough self-confidence, you might be able to fulfill your dreams like the little giraffe in ths Ecard which seems to be able to fly like a bird.