Hi Alexandra,
One example can be this; As soon as media broadcast horrifying happenings, more of the same is soon to happen. When they write about a school massakre, then shortly after you will always hear that there has been more schools being threatend. When media writes a big article about suicide happening alot more with teenagers than a few years ago, then suddenly several young people commit suicide. So, when we focus on the negative in our surroundings, and lots of other people do the same, then we're 'generating' a momentum of negative energy that will draw even more of the same towards us.
There is a great 'exercise' to do to really experience what a difference our own outlook has on our lives, I
think it's called the 30 Day Challenge.
For 30 days you are not 'allowed' to complain, talk bad about anyone/thing and work on always try to find a positive aspect in any given situation.
I'd add to refrain from watching/reading anything negative like the news or scary movies and only allow yourself to read/watch and talk about positive uplifting things. Do that for 30 days and see how much your own energy lifts.
Hope that explained my thoughts a bit better.
Moria x