Positive thinking, or optimism, is essential to your happiness and ultimate success. You will be happier, healthier, and more successful when you think positively than when you don't. You will be better, stronger, and more than you were before. Not only that, your positive outlook and actions will affect everyone you have an interaction with. You never know what's going on in the lives of others, and your positivity could help them have a better day. Your encouragement could inspire them to try a little harder and reach a little higher than they may have otherwise.
It's so important for you to think positively and develop more confidence that I want to encourage you to take steps to build up those things in yourself: read books that inspire you; spend time with positive people; find mentors who can help guide you; or even invest in time with a career coach who can help you find and eliminate thoughts or actions that you may not even be aware of that are holding you back.
Start here by reading my 7-part blog series on Positive Thinking in Your Job Search.
Best of luck!