Self-commenting
When you feel self-conscious, it's easy to overreact to your every mistake. If you trip over a word, you might apologize ("Sorry!"), make a joke ("No more coffee for me"), or resort to nonverbal reflexes like shaking your head or shrugging your shoulders. The problem with this "self-commenting" is your external preoccupation with your internal criticism. Mistakes happen; simply correct them without comment and move on.
Fast Tip: Fictionary is a game where players compose fake definitions of obscure words taken from the dictionary. Play it with your friends or family as a fun way to learn to ignore your inner critic.