How can I really build my confidence?

I think there are 2 types of confidence, the dumb type are confident even if they are full of shit and don't know what they are doing and there are people who will seem not confident until they have actually mastered something and then they are the best. I am like the second, every new task I wonder if I can do it, I take longer than others to get the basics but then when I get it, it takes no time I get better than everyone else. Try maybe talking to a close one about what you do to run the processes in your mind in a stress free environment or when at work try to help others with stuff you have mastered already, teaching something to someone is a good way to show yourself how much you have mastered what you know and build you confidence. good luck.