Very good thing and very bad things can happen in the same day. This morning, I had a class with a very good student who then proceeded to compliment me profusely. In the evening, I had a company class and I blew my stack at them. I told these people to stop speaking in Chinese and I told them and I told them and I told them.... Finally, I lost my temper. I wish I could have planned it but it just happened. I was shaking with fury and then felt light-headed. But it worked: they stopped talking in Chinese.
I am an easy-going guy so if I had lost my temper it was because they had gone too far. They had crossed the line.