The Happiness 'Pie'

Recently I got a hold of this book called 'The How of Happiness' by Sonja Lyubomirsky. A very interesting read. Some of the points mentioned were so deep and so refreshing. Like this one key concept she mentioned will stay with me forever. She splits happiness like a pie chart and divided the pie in to 3 parts:

l) 50%: unintentional/genetic;
2) 10%: circumstances;
3) 40%: intentional
 
So in essence she says 40% of what happiness we can bring in to our lives is completely in our hands!! Can you beat this??
 It does not matter whether we are rich, poor, lucky, fat or thin. Yes, about 50% of happiness does depend on our 'genetic composition' but almost as much has to do with us! This is supported by years of research and scientific data points. This felt so powerful and optimistic about how 'I' can choose to be either happy or not.
 
So some people just have ‘good set-points’ to begin with; rather they just got lucky and were born with a happy state of mind...but others who don’t have that should work for it. 
Just like how some people with 'not so great' metabolism have to work harder to look slim than those lucky ones who are just born with it... at least there is a solution and we are not just left to 'fate' or 'destiny' or some intangibles in life!
 
Work to be happy...  Isn't this one of the most productive, fulfilling goals to pursue??