I have believed for a very long time that what you put out in the universe is more likely to happen, so I have banished negative language from life. I used to say things like, " of course that would happen to me" or "knowing my luck xyz will happen." I had to consciously change my thinking to catch myself and erase such language.
I've worked very hard to put positive thoughts and energy out into the world. KARMA rules, so I purposefully make kindness matter. It is the every day little gestures or words to a stranger that often make the biggest difference. Someone can be having the absolute worst day, but a kind word or smile, letting someone ahead of you in line, holding a door, helping someone pick up what was dropped, etc. can be the bright light that lets their heart smile enough to improve their mood.
Moods and energy are contagious. If one bad mood meets another and another, it just brings a dark cloud over the area. A small act of kindness can bounce that light around and make the environment around us much sunnier. Amy Logan has written a book that wants to inspire everyone, starting with children, to go out and be kind because kindness matters.