Recently my friend Jess posted about being inspired by another friend, and basically what I came here to say today is: BE NICE.
You don't know what's going on in someone's else's world. That guy that cut you off on the highway might be having a bad day, or the worst day he's ever had. He might be struggling with something that you can only imagine.
Related, trust me: everyone, even grown men, can be bullied or taken advantage of. Stand up for yourself and stand up for those you love if they're too tired to do it on their own. Have faith in people when they've lost faith in themselves.