1. Get off the gerbil wheel
The more we think about a particular thing, our thinking becomes more habitual. If you go through the science of 'neuroplasticity'. Your brain tends to develop new and improved neural pathways in order to reinforce the repetitive thoughts and actions. If you indulge yourself in worry or fear-based thinking, you should definitely try to get rid of that gerbil wheel.
To interrupt the cycle, it's important to have an awareness that you are thinking a lot about your fears. By pondering on your fears and fear factors would only further enhance your fear rather than lessening it's intensity.

2. Low confidence does not define you
Do not lose your confidence level with small failures in life. When you lack confidence at a point of time in your life, you may feel you have lost everything. The feelings of lower level of confidence, if it has some grounded in some truth, do not define you whole life or your essential worth.
Most of us have small or big instances of insecurities that hold us back and makes us lack confidence from time to time. Confidence is a state of mind that would make you move past failures and flaws and will help you learn from them.

3. Understand the root cause
Very often the lack of confidence is situational. There might be something that has happened in the past that undermines your confidence in the present and draws out more fear to face the present situation. Other times, low confidence has longer, deeper roots or is connected to your personality.
By examining the reasons behind your confidence problems, you gain a certain control over them. When you recognize the root cause you would realize that it no longer holds the same power.