There are two layers in this question.
In the literal sense, they want to work because it does something for them. For some, work is means to an end. They want to do X but they can’t survive on profits from doing X so they spend some time working to do the thing that they feel actually adds meaning to their life. The other layer of this is the fear you are experiencing because you are staring into an abstract void. ‘Work’ can mean many, many different things. Quick peek at your Lemmy history says you have some interest in books. What if it was your ‘work’ to spend hours each day getting paid to read books, as an audio book reader, a literary editor, or something similar? What if it was your ‘work’ to spend hours each day being paid to write books as an author, or a journalist? Work can be hellish if you end up doing something you hate, for and with people you hate, to produce something you feel is making the world a worse place to live. It can also be a process of going somewhere pleasant, to do things you enjoy, with and for people you like, to produce something that you feel makes the world a better place. Work is just the label on the box. It doesn’t tell you much about what’s inside.