How do I get my students to care?

What do you do when students just don’t care? This is my first year teaching fourth grade and I feel like so often my students just simply do not care. When I am giving consequences they act like it doesn’t bother them (but they also don’t own up to behaviors). When I try to plan fun activities they say they don’t want to do it and just complain. I’m trying so hard, but I feel this is a fight I have almost daily with a few of my students. Anyone else have this struggle?