You are not born with lack of confidence. It is learned behavior for the most part. You only have to watch children racing around the playground aged five, not a care in the world and full of confidence and self-belief. But if as a child you were told you were not good enough or that you were lazy or that the other kid down the road was better than you then it is likely that you could develop self-esteem issues later in life.
As you get older your peer group can make you feel as though you are not good looking enough, you’re too fat or not clever or that you are clumsy or you don’t ‘fit in’. These feelings travel through your teenage years to adulthood when the same labels are given to you socially or in your place of work. Low self-esteem can make you feel worthless and self critical and can limit the belief you have in yourself, stopping you from achieving so many goals that you would go for if you had more confidence.