be a glutton for punishment idiom
吃苦耐劳的人，任劳任怨的人
to be someone who seems to enjoy doing something that you consider unpleasant
He's a real glutton for punishment, taking on all that extra work without getting paid for it. 他真是个任劳任怨的人，不计报酬地承担所有那些额外的工作。