What is happiness?

I've been thinking about happiness tightly but hard to say in one word.
What I can say for the answer now is;

Happiness lives with the heart who can feel happy to see other people happy.

When I see the little girls or boys have grown up with socialized and balanced mind I get impressed and great emotion of joy.
I found that good heart or positive impression inspire me great and strong.
If you bless someone you will be blessed instead...I think it natural.

Seeking for the happiness of the bluebird is to cultivate your own heart if you can feel easy with others including the environment.

Today is the Day of Children in Japan.
Wishing all children be happy.
I will give my good heart to them.