One thing that helped me a lot was doing some soul-searching. It's not so much about finding something to protect so much as realizing what I already care about, even if there are some layers of distance between my current feelings and that thing. I think that a lot of that listless feeling of not having something to protect is just sort of being distracted from what we actually care about. I would recommend just looking for anything you care about at all, even slightly, and just focusing on that feeling.

At least that makes sense and works for me.