Habitual mannerisms

Habitual mannerisms are things that have formed habits and are really hard to break. Does your character smoke or leave the toilet seat up all the time? Those are habitual mannerisms and everyone has some. Maybe your character likes to pace when frustrated or chews their lip or cheek when thinking. Maybe they play with their lighter when bored or strokes their mustache when thinking. Things like that they do without thinking and can make the character seem more real to the reader, as long as the actions are inserted correctly and not overdone. What are some of your habitual mannerisms?