Think of it like a backpack. On Monday I put in a pair of scissors. On Tuesday I add my pencil case. On Wednesday I add my calculator. On Thursday I add a ruler. On Friday I add my folders. Next week when I pick up my backpack, it's super heavy! But I'm confused because I didn't put anything heavy in my backpack. This is cumulative impact. You don't have to put something heavy in your backpack for it to become too heavy, everything together adds up!