One focus I think that is completely key to being a happy and a content individual is having the ability of distinguishing fighting for the right vs. fighting for hurt feelings. I freely admit that I still get upset when someone hurts my feelings, and it takes a lot to rationalize why someone would do that. The question that needs to be asked is, "Is it worth it for you to expend so much energy on one point?" If your answer is "yes," then go for it. Make sure that your argument sticks to the facts and does not focus on your feelings. You can express your feelings being hurt in a factual way instead of yelling and screaming. State what happened to make you feel that way, and you will be surprised at the reaction that you get from your adversary. Use a statement like, "When you did/said that ,whatever it is, you hurt my feelings."
Negative energy will eat you alive and strangely warp your inner self. There are way too may things in life to spend your precious energy on, like loving your children, your husband and your family. I like to think of energy. Why? There was this man who died a long time ago who believed that we are beings of energy and when we die our energy has to go somewhere. I think that he was a brilliant man. I am a little bit biased though.
I hope that you didn't think that my key to being happy was all sunshine and lollipops?