The cure for anything is salt, whether it be sweat, tears, or the sea.
So much wisdom packed in there. When I run in the backcountry it always involves sweat, and not infrequently involves tears. Not necessarily tears of physical pain, but I can recall many runs with companions--particularly in a race situation--where in the deep talk about stuff that seems to be invoked by the camaraderie, I have gotten moved to tears by the emotions of the tale.
Sometimes it's my tale, sometimes it's the other person's, but I've blogged before about how perfect strangers on the trail can open up about the most personal things so quickly, in a post I called "Sharing Secrets With Strangers on the Trail," here.
Needless to say, salt also looms large in our hydration scheme. Just like we sweat copious quantities of water, we also lose salt and other electrolytes that needs replenished as well. Many Ultrarunners use Succeed capsules during hot weather (I have no financial interest, Google it if you want more info), or make sure they ingest salty stuff along the trail.