The combined actions of individuals counts. You alone don't mean much (but if you happen to be the one who needs ICU care it matters to you), but when you and a million others avoid going out for anything other than groceries (washing hands well after that trip) there are many less opportunities for this to spread.

Obviously there are a lot of people required to get groceries to you, but if you are not in medicine or groceries stay home. That is a large supply chain but sti tiny and even those people are not going to other functions which reduces risk