Fear can hold us back in many ways. When we are fearful it can stop us from pursuing any of our goals. Fear also tends to take away security. When you are insecure you feel like your not in a stable place and there's a possibility that you'll feel like you are just not capable of reaching your goals. Insecurity caused by fear can also make you unmotivated to even try. It can also make you feel like you are just not good enough or that you could easily fail and not make it to your goal.
(That was just a small answer. obviously more could be added to it if necessary)
Fear is something that holds every back from achieving what they want. It can be a big or small thing, fear controls most people. If you have stage fright but would love to be an actor, your fear could hold you back. There is different degrees of fear. Not sure what you need this for, but the first answer is really good.
