Yes there are so many things I wish I could change, but I know I can't so I don't think about it much. The past is over now, all I have is the present and I have to try not to make the same mistakes again.
Like in my teens when I spent far too much time messing around on online forums, making my own and making fake accounts to make it look more popular. If I hadn't done that I could have put the time to better use, like my GCSE's, my other hobbies and interests etc.