For me, thinking about the possible (and for you, real) side effects of continuing to eat the way you do was well and truly enough motivation to stop eating the crap.
So do you like being able to see? How about walking, is that something you want to be able to do? Would spending time on a dialysis machine be something you'd rather pass on? (my father lost a kidney, not sure why, but I'm sure he loved the end result - not being able to hold on when he needed to pee). Stroke? heart attack?
These would well and truly be my motivators! (I only had to envisage sitting in a chair, drooling on myself because of dementia. And not knowing who these strange people were around me, my children and their families)