don't have any solution for the lack of motivation. I can make him do the damn work, but I can't make him care. Frustrating, but I don't know any way that my mother could have made me care about HS. I can expose him to a variety of life experiences and I can force him to attend school and do the assignments. I don't know how to force another human to give a damn. And I hope for him to find some inspiration somewhere sometime.
I have a teacher friend who had a son with Lack of motivation. I think it was his Junior year ( maybe sophmore ) year he flunked English - purely due to not careing. Instead of sending him to summer school - she sent him to the local community college - saying - this is college, it is different, you'll like it better, but you won't ever get there if you can't get out of high school. It did work. He never loved high school, but he did much better and is doing much better in college than he ever did in high school.