Stop asking HN for advice. You are getting "exercise more" and other platitudes. This is like asking your GP advice on software security and getting "install the antivirus thing" Self-esteem and confidence are very complex aspects of psychology. Ask a professional.
The idea is to reach out to people who made change to their life by some means, one of which could be 'Asking a Professional'. Exercising & Meditation are really really underestimated.