What advice would you give to your teenage self?

One thing that i really want my teenage self to do is to believe more in yourself . My lack of confidence, irrespective of the fact that i know the right thing to do made me guilty at the end of day. I worked upon this and am better then before but still when I think about those years it sometimes leaves bad taste in mouth……… …
Another advice that I want to give is try to express yourself little more otherwise one day you will realise that you have lost your expression entirely. You all know what people around call me stone hearted who is not able to understand other people and they are right because I kept my emotions and feelings to myself but I do want change and am currently working upon it…………