Speaking angrily

This quote is from Dr. Laurence J. Peter who was an educator and psychologist, by the way. It made me think about myself and showed me that I have to change immediately because the way I'm acting now is intolerable. Too often I let my anger speak without thinking about the consequences of hurting the feelings of others. This can be so easily avoided. So I've made one simple rule:
Never speak when you're angry.

Just let the other person talk and keep your mouth shut until the argument is over.

But as simple as it sounds, it's so hard sticking to that principle. Anger makes you blind and careless, so all the things you've intended to do or not to do are suddenly blown away. But I keep working on that since I believe that someday I will overcome this flaw.