They could workout to become stronger, look/feel, have better posture, and have more self-confidence. One way how I have become more confident about talking to people is just doing it. I'm an introvert that hates talking, but, by forcing myself to talk to people more I have noticed that I have become more confident about talking to random people. If your trying to talk to just one person you could learn more about them and what they like, and learn about what they like. So next time you see them you have something to talk about that they will also enjoy talking about.