I just saw this question on someone's twitter and I felt that I needed to speak about it.
Hate is such a strong emotion. Think of the amount of energy you spend when you hate someone. The majority of us go out of our way to mug or cut or eyes or dog them out to everyone around us. Yes, there are times when people make us mad or upset or do something just plain grimy. But to hate them means that you are wasting your good energy being consumed about a person who probably does not care about you.
This is why I also have a problem with grudges. And yes we are all at different points in our lives but just like hate, its cousin the grudge can consume your whole inner being as well. You loose sleep thinking about someone or a bad situation while that other person is going about their day like nothing had happened at all. It comes a time when you realize that and you learn to let things roll off your backs. The less people see you upset or mad the less they will try you because they won't even know what makes you mad or upset.
Just my observation.