I want you to try something.
For the foreseeable future, say something positive (in your head) about every person you pass. Seriously, do it. It doesn't matter if they are attractive, an ogre, a screaming child, a happy couple...whatever. It doesn't have to be a complicated thought either.
"They have a nice style, I can tell they have pride in their appearance"
"His nose has a lot of character"
"I bet she's a great grandmother"
It does NOT matter if this person is being an asshole, minding their own business, or already being kind to you. It does NOT matter if these things are true. These are merely thoughts echoing around in your head. The important takeaway is that you make the tiniest effort to notice something good about someone else. Once you become comfortable with this expand this out to your surroundings as well.
"It's a beautiful mother fucking day today"
"The air smells wonderful"
The reason I'm asking you to do this is because of reflections. Ever notice that when you are feeling great, everyone else seems pretty cool too? When you see someone being a dick (in real life or online) you are less likely to get sucked into their negative vortex, and just end up laughing about the fact that they are losing their shit. Likewise, when you are feeling down, it's easier to notice that everyone around you is being a jerk.
The way you feel about yourself is a reflection of the way you feel about your world and vice versa. Beautiful thoughts and feelings attract other beautiful thoughts and feelings. Negative thoughts and feelings are chum for negative feelings as well. Projecting positive thoughts into your brain about the world around you (even fabricated) positively influence the way you feel about yourself by inviting more positive thoughts and feelings your way. In a sense, it is a way to 'fake it till you make it' for positivity. Try it for a week and see how your outlook has shifted.
One more thing. With all of these positive vibes in your brain about strangers, make sure to share these thoughts about your friends, SO's, and family. It's strange to think about, but people don't really get compliments that often. When compliments are doled out, too often they are direct and to the point, and do not have thought put behind them. You'll make someone's day who is close to you, and spread your own positive reflection even more.