Habit Training - Temper #1

In Home Education, Charlotte Mason wrote about training the temper. "[A] self assertive, aggressive, self seeking temper is but too characteristic of the times we live in." The same was true then as it is now.
  
"It is very customary to regard temper as constitutional, that which is born in you and is neither to be helped nor hindered." Mason wrote that many parents attribute their children's attitude to nature.

And yes, according to Sonja Lyubomirsky in The How of Happiness, scientists do believe that half of our happiness (or what Mason would call sweet temper) is "governed by genes." Our life circumstances - factors like material wealth and beauty - affect only 10% of our happiness. That leaves 40%. Scientists believe that each person has control over 40% of his or her happiness.

2/5 of temper can be trained!

Mason wrote a lot about which habits a child should have, but very little on specific strategies and activities. How does one intentionally train a child to be sweet tempered?

I know that the obvious answer to this is by modeling a sweet temper. But what intentional activities can we do, modeling and with our children, that will train them in this habit?
 
Lyubomirsky offers twelve activities, the first of which is practicing gratitude.

Because yesterday was my daughter's birthday party, I talked to my daughter about thank you cards and had her start decorating cards for her guests. I am so grateful for the sweet friends who shared yesterday with us. I am grateful for getting to hug family - so much better than video phone calls! We work on saying thank you when we ask for things. And every evening, when we say bedtime prayers, I pray, Thank you for making this wonderful girl for Mommy and Daddy to love.

How do YOU teach gratitude?