Why do I always stay late at work even when I don't need to?

You stay late even when the work is done, because leaving while others are still there feels like quitting. Over time the long hours stopped being about the job and became about who you are. Now you cannot just go home, even when home is where you should be. Ask yourself honestly what staying proves, and to whom. Often it is a way of feeling safe, like being present equals being worth something. But hours in a chair are not the same as good work, and the people waiting for you at home notice the empty seat too. Being seen as tireless is a poor trade for an actual life. Pick one day this week and leave on time, while others are still there. Let it feel uncomfortable. Notice that the building does not fall down and no one thinks less of you. Do it again. You are not proving you can outlast everyone. You are proving you can decide when your day is done.