I don't know if you would call it learning but you can train to become confident. Its a two way mechanism, you need to be mentally confident and physically confident as the body is an easy give away of how confident someone is.
Most confidence (or lack of) is built on previous success (or failure).
Most people with little or no confidence are self consciously stopping themselves from building confidence because they usually think bad things happen to them or it never works out etc.
So step one is to think today....
'If someone else can do it, so CAN I.'
Lesson over.
B