Faith in yourself is the biggest test you will ever face. You can believe in anything you want but if you do not believe in yourself then you will always struggle to overcome the insecurities that constantly hold you back. Imagine you are in the water swimming along happily and suddenly you start worrying if your stroke is correct. Your arms suddenly feel heavy, you are conscious of your legs kicking against the water and you realize that you are not moving forward as swiftly and smoothly as you were before.
The insecurities are weighing you down, even though you were swimming confidently before. Gradually if you listen to the insecurities they will stop you moving forward and slowly pull you under into the murky realm of doubt. Try instead focus on your destination or goal. Imagine yourself there enjoying the achievement you have undertaken and feel yourself suddenly gliding through the water as if it were not even there. No resistance holding you back. We often over analyze ourselves to the point it holds us back. Believe in yourself and you will overcome any challenge that lies ahead.