Parenting Advice

Hi everyone, I am a single parent with two teenage boys, I work full time and try to provide my kids with everything I can. My oldest son is a good kid, he doesn't talk back and he is respectful. However I cannot get him to take school seriously, I have tried tutors and additional schooling, he goes to all the sessions but does nothing once he is there. I have tried to teach him about work and encouraged him to have a job during the summer, but he never takes it seriously and half the time doesn't end up going. I have tried punishments and taking things away ( he does not have an iPhone, or an iPad). He has played sports his whole life and I try to use that as motivation for him to keep his grades up, but now that he is in high school he simply doesn't care if he is on the team or not. I am concerned he will grow up and have no motivation to work or go to college. His behavior issues are not sever enough to send him to boot camp type programs. I am just lost on what to do next, I want him to learn how to work hard and be dedicated to something and I can't seem to get through to him. Does anyone have any suggestions or advice?? Thank you in advance, via /r/Parenting http://ift.tt/2xggLyG