Too much salt?

With the onset of hotter weather, I am curious if one can ingest too *much* sodium/electrolytes. I take Endurolytes as my primary supplement, plus I drink a low-sugar Sports drink containing sodium and potassium.

I never thought twice about it until I looked at a bag of Sun Chips, and notice that one serving of chips contained as much sodium as three Endurolyte capsules! (Chips containing salt? DUH!) A cyclist friend of mine once told me not to worry about it--that athlete's sweat so much they shouldn't worry about too much salt. Is he right, or should I still be careful?