I've taken a trick from Tenzig Norgay, who did a Tibetan milk sacrifice after ascending Everest for the first time. I don't deliberately waste any of it, of course, but a half-thermos of milk at altitude does do wonders for the strength.
Interesting, the name of the town in the last country, part of the first stop on this peregrination, comes from the word used for "reason" -- the south Slavic root common to the languages of Yugoslavia and nearby countries has a sense of things being visibly laid out, as in a vista of a valley between mountains, and uses it to describe a clarifying precept (not Reason writ generally, but a specific assertion). In fairness, the views of the valley from the mountain during the morning run were invigorating and clarifying, but the town itself usually seemed to be wrapped in a bit of a haze. I found the upper areas of the large mountain walkable from the nearby town to be much more mentally fortifying. Something about looking down on a panorama of mountaintop glacial lakes while suffering from moderate oxygen deprivation and exhaustion seemed to clear the haze of the mind. (And inspire some odd dreams later on.)