Every child is born with confidence. But it gets lost during his or her childhood. Parents, teachers and society at large are responsible for this situation. You came out of the womb blissfully unaware of external judgement. You were concerned with only your own experiences and needs. This is not to suggest that you should be oblivion to other people, but confidence was in-built during your birth. Once you developed a sense of self awareness, your became to harbour insecurities and doubts on how other people would see or judge you. Craving praise and avoiding criticism was learnt during this stage. The only thing that blocks your natural confidence is the train of thought that threaten it.
Since you have long lost your natural knack for confidence, getting it back will not happen overnight. It may take sometime for you to become more confident again. The first step would be to identify your strengths and weaknesses and then weigh these factors against what you most enjoy doing in your life. You need to direct your life on the path where your strengths mostly lie. In the meantime, you also need to devote time to improve your weaknesses. This is a starting point on your journey to become more confident in life.
You need to shift your mental focus to expect success in whatever you do. Even though conventional wisdom would suggest that you expect the worst in order to not be disappointed if you fail, pessimism would create a self-fulfilling prophecy in bringing you failure at whatever you do in life. This can worsen your lack of confidence even further. This is why you need to expect success in whatever you do in life. It will help you to build self-confidence in the long run.
Trusting your capabilities is another important factor in becoming confident over time. No one in the world would know everything. Everyone will be good at some thing and not so good at some other thing. Do not worry if you are not confident in what you can do now, be confident in your potential to learn it quickly. Seeing things this way will help to relieve yourself from judging yourself harshly. This is another important factor in developing self-confidence.
The aforementioned tips will keep you in good stead in becoming more confident in the long run.