One of my favorite sayings applies to this.
"Depression and Laughter are both contagious. Which one do you want to be spreading?"

Unfortunately, not everyone is equipped to handle depressive people. And it's exactly because it's such a contagious emotion. Your bad mood can easily drive someone else's happy mood straight into the ground and most people don't like that. But if you can get to a mindset where you are the one spreading the laughter, I think you'll find yourself overall in a better place, surrounded by better people.