Wise people have a quiet confidence. Unstable people (fools) feel the need to prove themselves, but wise people don't have to prove anything. They know they are capable, so they can get on with their work. Beware of showing off. If you are modest, people may not notice you at first, but they will respect you later.
"The wise don’t make a show of their knowledge, but fools broadcast their foolishness" Proverbs 12:23