Struggling To Finish A Book

I'm currently reading The Herbalist by Niamh Boyce but for some reason I'm struggling with it. It's very well written but I just can't get into it, possibly I'm just not in the right mood for this type of novel. I collected Joyland by Stephen King from the library this morning so think I'll read that now instead and then try & finish The Herbalist. I really don't like giving up on books but if you're not enjoying them why continue?