Impulse
I've always been plagued by mental problems, but I gotta know, is this anyone else? Whenever someone does something very litte, let's say, popped a guitar string. I wouldn't call it thinking really, but when they do something that miniscule I have this automatic thought to kill that person. Two seconds later, I know that I wouldn't do that to someone over just breaking my pencil I just bought for the rest of my money. I'm not lying, so please don't deem this fake. Has this ever happened to you?
I find it very beneficial to read up on psychological studies involving anger and violence. You will certainly glean a lot and likely able to correct your behaviour and free yourself from those thoughts all on your own.
A way to counter those negative thoughts is to force yourself to rationalise things all the time. Such violent thoughts happen when you are not rational -- for some reason. Try to be rational at all times. Also, think deep about what might cause the problem and try to find the reason -- as I said look up scientific studies on anger and violence. Look up as many of them as you can.
All the best and be happy!