When you go to the gas station, try to make someone smile with a good natured joke or comment, etc, If you're in a store and see someone confused about something you may know about, give them a advice or a hand. (i.e., I do this when I am in Home Depot and see a lost soul. The most common response, "thanks, I don't run into people that like to help much". By helping others you are helping yourself. Good combo.
As for the state of humanity as a whole, well that's another kettle of fish. Different things may work to knock you out of a slump. Find the most beautiful piece of music you have and sit back and think that only a human could have created it. Something classical usually fits. Same with your favorite book or movie, especially comedies. Strangely, in a down spin a few years ago, I saw two movies around the same time that knocked my perspective back into gear, "Cloud Atlas" and "Oblivion". Something else may do it for you.
If you are really up to it, try "Life of Brian".
Enough ramblings maybe this helps..