How much sodium do you need to eat?

I've searched but could not find anything via google or on Reddit that I am looking for. When I search, everything says to not eat anymore than 1500mg of sodium/day So I assume that is the upper limit, don't go over that number. My question is, how much should we be eating? I know it is important, so it shouldn't be completely absent from your diet. I prepare all of my food and haven't been using the salt shaker so I am going to start adding salt but am unsure as the how much is a good healthy amount. Also I run ~13 miles a day