I did nothing in high school but graduated minimally ( 50 – 60%) how should I turn my life around?

When I was in high school I spent my time pretty much doing nothing. It wasn’t because I was off skipping classes or doing drugs I just never could rap my head around doing homework or actually studying. Anyways, now I’m graduating with 50 – 60% average which is probably not even going to get me enrolled in Douglas collage (haven’t even applied for that too) I really want to turn my life around but don’t know where to start? Should I retake my academic course like English and Math? Or should I just look for a job? I wanted to become a judge but with discipline like mine that not going to happen, so how should I discipline to actually get stuff done advice would be nice. 