a creature of habit 墨守成规的人（非正式）

英文释义

A person who usually does things in the same way simply because they are his habit, rather than being his conscious decisions.

例句

My father is a creature of habit who has eaten lunch in the same restaurant near his office every day for thirty years.

我的父亲是个墨守成规的人，30年来每天都在公司附近的同一家餐厅吃午餐。